From 1930 onwards began to manufactured homes outside the castle and the stables converted into new houses by adding rooms or floors. These are called xokastra. Inside the castle there were about 400 houses, all three floors and built to each other, with narrow streets that only fit man to pass. Typical fortified settlement once reached the 4000 souls according to witnesses visitors.
On current form he took in 1413 with the restoration of Giovanni IV Quirini. Built on a plateau 4,000 sq.m. selected for the defensive positions of the residents. The wall of the castle, forming a ring that essentially consists of two parallel walls in between the free spaces are formed in housing. The only entrance is flanked by two strong towers built with cornerstones.
The interior is built with low stafrolitho (an undeniable element of Frankish architecture). On the basis of the entrance portico which opens the right and left are stone benches that were used to sit and rest the people making social contacts and trade.
On the south side of the castle is the other tower, four stories known as Sarai and gazing over the sea. The castle had excellent drainage to ensure healthy living for residents.
The Astypaliotes day working out on land and in the evening in the castle closed from fear of robbers - pirates. Over the door of the castle is still a hole, the murderer, which threw hot water or let free bees to chase the robbers.
Major surgery at the gate of the castle is the construction of the temple dedicated to the Virgin Mary Annunciation. Built in the 19th century was demolished in 1853 as the residence of the Venetian family Quirini.
Inside the castle is the oldest church of St. George which was built in 1790. The space in front of the church was the Blatsa (square) where celebrations were feasts and dances of castle.
The castle suffered damage from earthquakes, bombing the Germans but also from the people who took the deserted houses of the building materials to build houses out of it.
Today it attracts visitors to the island without any special role in the life of modern Astypalaia.