Its orthogonal drummed small domes are ornamented with brick decoration. It is one of the very few churches with 2 levels. In the east side of the church, under the bilobed window of the apse there is the entrance to a crypt, in which you can get to through a small staircase. This crypt served the purpose of a cemetery, in other words it was a place were the guards of the castle were buried. The cemetery character of the crypt of St. Nicolaos is reinforced by the few graves' remnants and homan bones that were found.
According to a document dated between 1339 and 1342, and also the shape of the church's stonework we can conclude that the church of St. Nicolaos was built before the Serbian occupation and more specifically in the first half of the 14th century (Paleologi period).