The ruined fortress Belvedere or Rizokastro, the seat of the homonymous Castellana during the Venetian occupation, is located on the hill Kastellos northwest of the village Kastelliana, where in ancient times the city of Priansos was sited. Inside the fortress there are the ruins of the Early Christian Basilica of Priansos with a mosaic floor, as well as six temples. The three of them, including the domed church of Saint George at the peak, are completely ruined. The surviving churches are Saint Anastasia, Kato Panagia and Pano Panagia.
The church of Saint Anastasia is located in the southwestern part of the castle and was built, according to Gerola, on the ruins of two ancient cisterns. Due to its small size, the fragmentary iconographic program, dated to the middle of the 14th century, bears only a few frescoes. The arch hosts four scenes from the Christological cycle (Birth, Baptism, The Joy of Myrrhs, Ascension) and five rare scenes from the life of Saint Anastasia of Sirmium.