Nikolaikirche, Gothic church building in Geithain, Germany.

Nikolaikirche in Geithain is a stone structure with two square towers rising from its western side, topped with pointed roofs. The building displays a clear geometric form with a rectangular floor plan and multiple window openings along its exterior.

The two-tower west front survives from a Romanesque basilica, comparable to the church of the nearby Wechselburg monastery. In the 14th century the Romanesque choir was replaced by a Gothic choir twice its size. The three-aisled hall church was begun in 1504, partly demolishing that choir; its planned vault was never built and a flat ceiling was installed, painted by Adam Schilling in 1594/95.

The flat wooden ceiling, painted by Adam Schilling in 1594/95, shows the Saxon electoral coat of arms, the Trinity, the Brandenburg eagle, the Baptism of Christ, the Bünau family arms, the Last Judgment and the town arms, with the apostles along the borders. In the north aisle are Saint Nicholas and a portrait of Philipp Melanchthon; in the south aisle, the artist's coat of arms and a portrait of Luther.

The nave measures about 30 metres long, 24 wide and 14 high, with rows of pews along a central aisle leading to the choir. The west entrance is through a Romanesque portal with a stepped, three-fold surround. The choir, which was shortened when the nave was built, ends in a slightly irregular five-eighth close.

The Romanesque west portal has a three-stepped frame with three-quarter columns whose capitals carry palm-leaf and interlace ornament, and the tympanum is carved with interlace. The west facade above it holds a group of three pointed-arch windows, probably from the 14th century.