The small lush green peninsula separating the old from the new harbour is called Bourtzi, and in 1207 the Gizi brothers built a small Venetian fort on its edge as an attempt to protect themselves against the raids of pirates. As it resembled a small island, unfortunately it failed to bring the desired results, thus creating the Castle, in the northern part of Skiathos to protect its inhabitants.
In Bourtzi, besides the fort, there was a water tank and the chapel of Agios Georgios, patron saint of Venice, to which the Kastelli tou Agiou Georgiou (Castle of Saint George) owes its name. In 1660, when Skiathos was occupied by admiral Morosini, the fortress was destroyed, with its ruins as well as those of the church and the tank being a reminder of the past until today.
After the liberation of Skiathos from the Turks, Bourtzi operated the first quarantine while in 1906 an elementary school was built at the centre of the peninsula (nowadays it functions as a cultural centre) with the donation of AndreasSyngrou, while in 1925 the bust of Alexandros Papadiamantis was also placed at the school.