Kastelos Hill, situated 8 km west of Chania city and 1.5 km east of Varipetro village in the Kydonia province, is in close proximity to the Transfiguration Monastery at Varypetro. This walled citadel (acropolis) stands at an altitude of 250m and is believed to have been inhabited from the Minoan Era through medieval times. The majority of the walls, which are preserved in their full length and nearly their full height, date back to the Byzantine period. On the south and west sides, the walls enhance the natural steep fortification, while a double row of walls with bastions can be seen. Traces of older fortifications can also be discerned at the lower part of the hill.

Remnants of buildings are scattered throughout the citadel. These structures were organized in clusters, with many carved into the rock. Excavations have uncovered buildings from the Hellenistic and Roman periods, while a Late Archaic cemetery with jar burials was revealed near the Agia Kyriaki Monastery.