The Kastro according to the prevailing view was founded in the 14th century, around 1360. Due to piracy, the Skiathos left the Byzantine city, which was where the city of Skiathos is today, and built the medieval settlement of Kastro, at the northern end of the island. As the fortress was inaccessible from the sea and the entrance to it was possible only with the movable wooden bridge, it provided the inhabitants with relative protection.

The Castle was under Byzantine rule from 1360 until the fall. In 1453 it was taken under their protection by the Venetians, on the condition that they respect the old privileges of the Venetians. Gizi. In 1538 he occupied the Castle Καπουδάν πασάς του Τουρκικού στόλου Haireddin Barbarossa. It remained under Turkish occupation until 1821, while in 1660 for a short time it returned to the Venetians after the siege of Francis Morosini. Kapudan Pasha of the Turkish fleet

In 1829 the Skiathos left the castle and returned to the old Byzantine city, the present city of Skiathos. When they left, however, they did not take only their household. They removed from the houses and other buildings, whatever building materials they could use again, such as frames, windows, doors, roofs, timber. For this Castle was deserted abruptly. Of the approximately 20 churches and the five hundred houses, today the two parish churches survive, the Church of the Nativity of Christ and Agios Nikolaos, two more have been renovated, the Church of St. Basil and St. Marina, the Mosque of the Turkish Command, the drinking water tank in entrance and the cistern of rainwater in Christ, the gate with the scalpel and walls around the Castle, while the loopholes are in good condition