The church of Agios Nikolaos is located at Mesorouga in Alagonia. It belongs to the architectural type of the domed free cross and dates to the 14th century. The ceramoplastic decoration at the drums of the transverse arms of the cross, along with the dome’s morphological features, confirm the close affinity of the local workshop with the architectural tradition of the Despotate of the Morea. The dome and the cross arms were extensively repaired in the late 17th century, following large scale destruction. The surviving wall-paintings were made after this incident and the retaining arches supporting the dome were added shortly afterwards. Smaller scale repairs were made in 1836, mainly at the western cross arm and at the door openings.

The wall-paintings are limited to the dome and the altar and belong to a single phase, dating to the second half of the 17th century. Part of a possibly earlier layer has been located at the north wall of the western cross arm. The church has been restored by the Ephorate of Antiquities of Messenia.