The place where the heart of Nafplio beats. Around it, all the aspects of the city are concentrated: the historic, the commercial and the touristic. Its street plan reminds a lot the rectangular squares of the cities of southern Italy. The many names awarded to the square from time to time underline its historic role. During the Venetian rule (1686-1715) it was called Piazza dei Armi (Arsenal Square) because the Venetian arsenal (Armeria) was located there. During the War of Independence it was renamed "Plane Tree Square" because the "Dimogerontes", the town's elders would congregate under a plane tree. King Otto named it "Ludwig's Square" to honour his father. Its present name was given to it due to the movement of the 3rd of September 1843 when the Greek people demanded a constitution from Otto. Here, was where the incident with the notorious Psorokostaina took place: she is said to had offered her humble belongings, a silver ring and a Turkish silver coin to help the revolutionaries struggling to survive in the Missolonghi siege.
The most important buildings of Nafplio are situated around the square and are transform depending to the era: the building that hosts today the Archaeological Museum was once the Venetian arsenal, while later it hosted the first Governorate of the newly-formed Greek state. The building next to it used to be the mosque that Aga Pasha Delviniotis built; later it was used as the first Parliament of the Greek Nation. Behind the Parliament, the Turkish "medrese" (Islamic school) housed the "Leonardo prisons" after independence. Moreover, the houses of the fighters were also here. Kolokotronis' house is still standing and opposite it, the house of Nikitaras. A branch of the National Bank is now operating at the premises of the house of Calliope Papalexopoulos, the rebel of the Revolution of Nafplio (1862) and next to it, Trianon Theatre is operating at the old Ottoman Mosque.