St. Michael's Fortress in the Croatian town of Šibenik (formerly known as St. Anne's Fortress, Croatian: Tvrđava sv. Mihovila, Venetian: Castel vecchio) is a medieval fort situated on a steep hill above the old historic center of the city. Its strategically favorable and dominant position made it the central part of Šibenik fortification system. The location was more or less continuously occupied since the Iron Age, as is witnessed by numerous archaeological findings from the era. The city of Šibenik was first mentioned on Christmas Day of 1066 in a charter signed by King Petar Krešimir IV and verified by his courtiers. It is widely considered that the signing took place at St. Michael's Fortress.