The fortified settlement of Agios Konstantinos (7th- 10th century) is built on the north mountainous slope of the island. It is accessible by two ways. Via footpath, this begins westwards of the church of Agios Vassileios and leads to Agios Konstantinos after an hour of walk. The second and easier is by ship, which leaves the visitors on a small bay. From there it's a sort walk to the Byzantine fortified settlement, with houses, cisterns, fortified walls and the ruined church of Saints Constantine and Helen. At the Holy Bema a unique fresco with a cross, decorated with painted jewels (7th cent.) still stands today.
Source: www.kalymnos-isl.gr