In the early 19th century, the population of Syros consisted of a small community of Catholics residing in present-day Ano Syra, who enjoyed the protection of the Holy See. With the outbreak of the War of Independence, Syros decided to remain neutral, which would play a decisive role in the development of the island. Its safe and protected port would attract many refugees, who would add to the island’s population and lead to its unprecedented growth over a short period. Thus, Ermoupoli was founded shortly after 1821 by refugees from the eastern Aegean and the Asia Minor coasts, who named the new city after Hermes Kerdoos and Hermes Logios. According to Tim. Ambelas: "After the outbreak of the Greek revolution, given the neutrality of the inhabitants of Syros, the island of Syros was considered to be the safest refuge for the persecuted Greek families that survived the terrible annihilation after the turmoil suffered by the Greek cities". Thanks to the hard work and expertise of the settlers, the new settlement had already started to flourish economically, culturally, and intellectually before the middle of the same century. With the creation of the first Greek State, Ermoupoli also emerged as the largest port in the country. The elaborate public buildings, the beautiful urban mansions, which reflected the robustness and high intellectual level of Ermoupoli society, presented the image of a European city in the heart of the Aegean.

The new settlement was created entirely by refugees and not as a suburb of an already existing city. The destruction of Kydonies (1821), Chios (1822), Psara, and Kasos (1824) were the main causes that led thousands of civilians to settle on the deserted coast of the island. Most of the first settlers of Ermoupoli were former inhabitants of Kydonies, Moschonisia, Chios, Smyrna, and Psara, namely, populations of the Eastern Aegean and the Asia Minor coast. For the first two years there were only wooden sheds on the shore, where most refugees spent their days or which they used for their trade activities, while they spent the night in Ano Syros. From 1823 onwards, the sheds were replaced by small stone houses and warehouses, and the city neighbourhoods started to take shape. The large two-storey mansions started appearing in 1825, according to sources, when the two-storey house of G. Petritzis, the future mayor of the city, was built.

Industrial activity was first observed before the mid-19th century, with small iron and leather processing installations. However, after 1850, when most factories became steam-powered, industry evolved rapidly with the establishment of major industries and large factory buildings. According to the 1879 census, there were 23 factories operating in Ermoupoli, 16 of which were steam powered. However, in 1880 Ermoupoli suffered a severe blow to its economy, with all important sectors declining. Due to intense competition from other newer ports, combined with political developments in the broader region, transit trade started to wither away, sail shipping declined, and so did small cottage industries. During this difficult period many craftsmen left the city. Just before the end of the 19th century, the economy in the Cycladic capital recovered, having turned to new sectors. New factories appeared, most of which processed cotton. Also, the first steam-powered fleet was created with the help of the city’s powerful merchants, which financially strengthened the port, as well as the city’s machining centres.

The economic development in Ermoupoli led to a flourishing of the arts and letters. Academic and vocational schools were established. Sources inform us that in 19th-century Ermoupoli there were 10 state schools and 8 private schools. Also, from the very first years of its foundation, numerous newspapers printed in local presses were in circulation; in fact, some of them were bilingual, printed in Greek and French, addressed to upper-class educated readers. Furthermore, theatres, operas and artistic events indicate a rich artistic scene in the Cycladic capital and an art-loving public.

The construction of the church of the Transfiguration of the Saviour began It was the first church of Ermoupoli and the present-day metropolis of Syros’ capital. It was dedicated to Christ to express the gratitude of the refugees for being saved. According to Tim. Ambelas: "Those who assembled by the thousands on the deserted shore of the island felt the need for a church, so as to pray to the Almighty as long-suffering people and as Greeks awaiting the resurrection of the struggling Greek nation”. The church was built in the architectural style of Panagia of Tinos, the foundations of which had been laid a year earlier. It has even been suggested that the two churches are works of the same architect. According to Ambelas, tents were set up in the church courtyard and served as a hospital. Furthermore, this is where city assemblies took place in the early years and important decisions were made. It was, in fact, at such an assembly in that very year that the new settlement was officially named, which, until 1824, had been called Syros, so that it could be distinguished from the old settlement, Ano Syros. Thanks to the proposal of elder Loukas Rallis, originally from Chios, the new trade city was named Ermoupoli and was placed under the protection of Hermes Kerdoos and Hermes Logios. Currently, the Church of the Transfiguration houses relics and icons of the 19th century, as well as the tomb of priest Anthimos Gazis, a prominent figure of the Modern Greek Enlightenment.

Thanks to the Alexandros Axiotis, local Provincial Governor of Syros and Mykonos since late 1824, both Ano Syros and Ermoupoli stopped paying tribute to the Sultan, and so the island emerged from neutrality and was in favour of the struggle for liberation. The Sultan issued a firman read publicly in Smyrna in February 1825, according to which Syros was characterised as an enemy of the Ottoman Empire.  

The first public hospital in Ermoupoli, and the Greek territories, was founded with sponsorships mainly by Milionis of Rhodes and Chatzis Dimitriou, as well as other Ermoupoli merchants. Starting the very next year, when it was completed, the hospital received its first patients, among them many fighters of the Greek War of Independence. Its main donor died before he had the opportunity to see the project completed. His tombstone is located in the current hospital of Syros. This historic building, which now houses the Aegean Casino, was the first public building of Syros.

Ermoupoli participated by proxy in the Third National Assembly in Troizena, as it was already one of the most populous cities in Greece, with a population of approximately 13,805, according to the following year’s census. The first elected representatives of the city were: Argyrios D. Tapochtzis and P. Omiridis.

Construction of the church of the Assumption of the Virgin began in the Parianon quarter, with expenses paid by D. Platanitis from Hydra. Until then, most residents attended the Church of the Transfiguration, and the rest went to the Orthodox churches of Ano Syros; so, the need to construct another church in Ermoupoli became apparent early on. It is worth mentioning that in 1983 a work by Domenikos Theotokopoulos was discovered here, among the holy icons, depicting the Assumption of the Virgin, and bearing the signature of the great Cretan painter.  

Upon the creation of the Greek state, the port of Ermoupoli became a centre of transit trade. Textiles, leather, and hardware trade flourished. This resulted in the creation of a strong banking system. Banks were established and, in fact, in 1845 Ermoupoli had its own branch of the National Bank of Greece.

The anti-Kapodistrian movement emerged in Ermoupoli, due to the new bills imposing reforms and taxation on trade. During their announcement at the Church of the Transfiguration, Ioannis Peridis from Chios, a member of the local Elders’ Council, roused his fellow citizens in a generalised reaction against the Governor, shouting: "Having once broken the Sultan's chains, we shall accept no new chains. No one received an order from our nation to subject us to the yoke.” Protest took place in the streets of the city, the leaders of mobilisations were arrested and imprisoned, with the intervention of Kapodistrias himself, who arrived in revolted Ermoupoli a few days later.  

Streets, squares, and the city zone were identified. A sewage system was established, the coastal road was cleaned, and two main roads -the coastal road connecting the city to the countryside and the road leading to Vaporia neighbourhood - were made widened. Construction of large-scale port works began that very year. They would transform the natural bay of Syros into an important port. On January 15th of the same year, foundations were laid for the Transit Warehouses, the Customs House, and the Lighthouse on the small island located in front of the port, known as Didymi or Fanari or Gaidouronisi. The buildings were constructed at royal expense, at the request of Loukas Rallis, an Elder Council member of Ermoupoli, and they were designed by Bavarian architect J.B. Erlacher. The Customs House was the first public building in modern Greece. There was also a gunpowder warehouse on Ermoupoli coast, for the safe storage of gunpowder, which was a tradable good. Until then, this flammable material had been stored in various parts of the city, endangering the safety of Ermoupoli. The cemetery in Agios Georgios was inaugurated. The south wing stands out with a rare set of sculptural and architectural works.

After 1830, when Ermoupoli had taken shape, new hamlets started being created just outside its limits, which functioned as summer holiday homes for wealthy Ermoupolites. Perhaps the most representative of them are Episkopio, Chrousa, and Poseidonia. In these villages, in between the homes of present-day residents, wonderful country villas emerge; old mansions of exceptional architecture, surrounded by green, still retaining their former glory.

The oldest of these is Episkopio or Piskopio, just 4.5 km from Ermoupoli. Just outside the village, an old church, Panagia Piskopiana or Protothroni, is, according to tradition, the first seat of Syros, and the remains of the Catholic bishop’s residence from which the settlement took its name are preserved to this day. Beautiful neoclassical buildings, that belonged the wealthy Syros vacationers from another era, and a Club are preserved in Episkopio. Particularly interesting is the abandoned ‘Kokkinospito’, an old mansion which was the inspiration behind Karagatsis’ novel ‘The Great Chimera’.

Later, Chrousa was created in the southern part of the island, 8.5 km from Ermoupoli. In the centre of the hamlet, the Orthodox Church of the Assumption of the Theotokos was erected in 1854 by the citizens of Ermoupoli who moved here in the years of the cholera epidemic, in order to protect themselves from the deadly disease that plagued crowded urban centres at the time.

A more recent hamlet is stately Poseidonia (Delagratsia), built on the southwestern tip of the island with a coastal front facing the bay of Finikas. It is named after the ancient Temple of Poseidon located in the broader area However, it is also known as Delagratsia because of the small Catholic Church of our Lady of Grace (Madona della Grazia), which is built in the northern part of the village.  Excellent examples of a upper class summer residences are Villa Valmas with its imposing tower, Villa Psiachi, Koulouris Tower, etc. Also characteristic is Villa Tsiropina, which used to house Poseidonia Town Hall. It is currently a Cultural space that holds a multitude of theatre, music, and art events, and also houses the Centre for Environmental Education (KEPEA). Just outside Poseidonia is the Catholic Church of Panagia Faneromeni, which was built in 1890, next to an older 17th century church. Today, the church is a pilgrimage for Christians from all over Syros and the rest of Greece.

Syros Gymnasium (Lower Secondary School) was inaugurated. The school was located near the Church of the Transfiguration, behind the Municipal Mansion. The building, designed by architect J. Erlacher, housed the first lower secondary school in Greece and it had been in operation since 1833. The first principal of the lower secondary school was Neophytos Vamvas, one of the “Teachers of the Nation” and a representative of the Greek Enlightenment. Many important figures were to teach here, and many students would become prominent figures in the political life of Greece, including Eleftherios Venizelos.

Georgios Petritzis, originally from Smyrna, was the first ever mayor elected in Ermoupoli. He served as mayor of the city until 1837.

The reconstruction of the old Lazaret began at the port of Syros; a project by architect W. Von Weiler. This was the temporary accommodation of those arriving from Egypt, Constantinople, and other places where there was a risk of spreading epidemics and cholera. The Lazaret was very busy during the first half of the 19th century when strict sanitary measures were put in place. During the second half of the same century, traffic declined until it was finally abandoned and the Drydocks were built in its place in 1870.

A public building was constructed on the beach of Ermoupoli that stood out for its size and architecture. It was the Butcher-Fishmonger Shop, which was demolished, and in its place stood the building of the Public School of Engineers of Syros. It currently houses the Decentralised Administration of the South Aegean. As seen from surviving photographs and sketches, it was a two-storey building with a gabled roof and arched openings. Several years later, in 1872, a unique public building was constructed for the Fishmonger shop in the ‘coal sellers’ square’.

The magnificent church of Saint Nikolaos of the rich, patron saint of the city, was built in the Vaporia aristocratic quarter, designed by architect Ger. Metaxas. The domed basilica with its characteristic blue dome and tall bell towers is undoubtedly one of the most impressive churches in Greece and one of the largest in the Balkans.

During the Crimean War, French warships occupied the port of Ermoupoli, after the Franco-British fleet had landed in Piraeus. The occupation of the country’s largest ports aimed at averting Greece’s involvement in the Crimean war and ensuring its neutrality. However, there were outbreaks of cholera among the French troops, which was plaguing Southern France at the time. The disease spread rapidly throughout Ermoupoli and Piraeus, causing thousands of deaths.

The first underwater pipeline to be submerged in Greek waters arrived at the northern side of the port, connecting Syros to Piraeus by telegraph, later providing a connection to Chios and Constantinople. In 1878, the Eastern company turned this facility into its telegraphy station in the eastern Mediterranean. Two years later a two-storey building was constructed behind the Transit Warehouses, which housed the company’s offices until 1925. It is a symmetrical building, with many openings and a balcony with impressive corbels on the side of the road. It currently houses the Merchant Marine Academy of Syros - Department of Deck Officers.

In 1860, Ermoupoli is already the first commercial port of Greece. In the summer of the same year construction began for a separate Customs building, which was originally housed on the beach of the port, near the central square. The new building, designed by Georgantas and completed in 1861, according to historical sources, had an impressive façade with double and triple lancet windows on the first floor and arched openings.

The Greek Steamship Company, which had taken over domestic ferry transport since 1857, inaugurated its ironworks. This new steam-powered plant was built in the location of the old Lazaret and was designed by European architects. “It is first among all the factories in the East”, and was justly the pride of the Ermoupolites, as made evident by the enthusiastic publications in the local press of the time. Boilers, engines, and all kinds of tools were manufactured here. The factory also included a drydock in which Greek and foreign ships were cleaned and maintained. In 1898, after the Hellenic Steamship Company went bankrupt, the factory would pass into the hands of the ‘Syros Drydock & Ironworks’ company.

Ermoupoli acquired a public clock and this was a privilege that no other Greek cities of the time had. The clock, manufactured by clock makers in Munich, was placed on a tower in the eastern part of Ermoupoli and was visible from many parts of the city.  

Club Hellas was built to house the two clubs of the city. The building with its marble façade, ornate balconies, and beautiful interior ceiling murals was designed by architect P. Sampo. It had a reading room with Greek and foreign newspapers and writings, a billiards room, a lecture hall, and a café, and it was where 19th-century Ermoupolites entertained themselves, socialised, and informed themselves. It is also worth noting that the dances, philanthropic celebrations, and receptions of the Ermoupolite elite would also go down in history. Currently, the building houses the Municipal Library of Syros-Ermoupoli. The green space, which has been shaped in front of the building, is decorated with the busts of G. Souris, Emm. Roidis, D. Vikelas, Rita Boumi Papa, Tim. Ambelas, and K. Bastias, intellectual figures of Syros.    

The Club is currently operating as a Cultural Centre, housing the Municipal Library of Syros-Ermoupoli The building also contains two meeting rooms, one arts room, the exhibition of Cycladic copies, as well as the Asia Minor Memory Shelter.

The emblematic building of Ermoupoli with its austere façade was built at the expense of the Ermoupoli residents and was designed by the architect P. Sampo. The interior, in contrast to its austere façade, was luxurious and was a miniature version of La Scala in Milan. It was inaugurated on 20 April 1864 with a performance of Verdi’s opera ‘Rigoletto’, and in the years that followed the theatre hosted many famous foreign and Greek artists. Among them was the queen of Greek theatre Marika Kotopouli (1953), in the play ‘The Shadow’ by Nikodemi, which was the last performance before it was abandoned. The building was in ruins for many years. Since 2000, the building has been restored and it now hosts theatrical performances, operas, musical and artistic events, and festivals.

Ermoupoli participated in the movements against the monarchy of Otto. After the events in Nafplio on 31 January, a new uprising began in Ermoupoli. Ermoupolite rebels, along with some Tinians and led by Leotsakos, Moraitinis, and Skarvelis, having commandeered the ships of the Greek Steamship Company, were heading toward Kythnos to liberate political exiles. There they clashed fiercely with the government army, resulting in the death of the three leaders. Thanks to a shot fired by the government ship ‘Amalia’, commanded by Leonidas Palaskas, the rebels were stopped. Despite the failure of the uprising of Ermoupoli, revolutions would flare up again in October of the same year and Otto would eventually be driven out. After the removal of Otto, the central square of Ermoupoli (currently Miaoulis Square), which bore the name of the king, was renamed Leotsakos Square. Two other large squares in the city were also given the names of the other two rebel leaders, Moraitinis and Skarvelis. A relevant article in the newspaper ‘Astir ton Cyclades’ (Cyclades Star) on 20 October 1862, states: "... moreover, our Municipal Authority, in memory the noble children of the Homeland who sacrificed themselves for this salvational change, Leotsakos, Moraitinis, and Skarvelis, renamed each of the three Squares of our City, giving to each one of the names of these patriots…”

With the declaration of the Cretan Revolution, Syros provided financial and other support to the struggle. It offered refuge to persecuted Cretans and became a resupply centre for the Revolution, with the help of the Greek Steamship Company, which made its steam ships available for this purpose. Among the Cretans who arrived was a young Eleftherios Venizelos, who temporarily resided in Ermoupoli with his family from 1869 until the end of the Cretan revolution.

The Greek cruiser, that had successfully participated in the Cretan revolution, had become the target of Hobart Pasha, leader of the Turkish fleet that had cut off Crete. The latter, having failed to defeat ‘Enosis’ in Cretan waters, decided to ambush it as it was returning to Syros. So, on 2 February at dawn, the Ottoman fleet approached ‘Enosis’ outside the port of Ermoupoli. So, on 2 February at dawn, the Ottoman fleet approached ‘Enosis’ outside the port of Ermoupoli. The alarm sounded immediately and both sides exchanged fire. The Greek cruiser accelerated toward the port, but before distancing itself it succeeded in causing damage to two of the Turkish ships, one of which was Hobart’s flagship.  

A mansion was built by the Municipality of Ermoupoli, designed by architect I. Vlysidis, above the church of the Transfiguration. It has been the seat of the Metropolis for many years. From 1903 to 1907 it housed the Higher Municipal Girls School. The same architect designed the Municipal Warehouses, which were also built that year.

The Charitable Society of Ermoupoli, which operates to this day, built a house for the poor. It was completed with the church of St. Panteleimon in 1883.

The foundations were laid for the island’s city hall on the north side of Miaoulis Square, designed by German architect E. Ziller. Its construction was completed in 1898 and it was one of the largest city halls in the country and undoubtedly one of the most impressive. It was a large, imposing, two-storey building, which visitors could see from afar, upon entering the port of Ermoupoli. The façade is dominated by rich architectural decoration and an all-marble propylon, crowned with a pediment, forms in its central portion, while two towers stand in the corners. It is a jewel of Ermoupoli, which currently houses municipal services, the Courts, the Land Registry, as well as the Archaeological Museum of Syros.