The Castle of Guerini or the Venetian Castle is the trademark of Astypalea located on top of a hill in the main town. The walls stand until today but the constructions inside the walls are ruined. The castle was constructed by John Guerini  an Italian noble who took over Astypalea after the siege of Constantinople by the Cruzaders in 1204. It was built to protect  from pirate invasion. Inside the walls you can visit the beautiful church of Panagia Kastriani, the church of Agios Georgios and the Tower of Saray. The castle offers a panoramic view of the Town of Astypalea.