Ai Nikolakis is a small two-storey partly ruined church northeast of Kastania. The ground floor is single naved and barrel-vaulted. The upper floor, also single naved must have been domed, but the dome has collapsed. The upper part of the semi cylindrical apse has also collapsed. An entrance is opened on the west side of each floor. The church is built with rubble masonry; remains of a dented band are preserved above the arched entrance of the first floor. Two-storey churches are rare in byzantine architecture and have been associated with burial functions. This one was probably a funerary chapel. The wall paintings are very fragmentary; they date to the mid- 14th century, which is probably the period of the church’s construction.