Mengerskirchen Castle, Medieval castle in Mengerskirchen, Germany.

Mengerskirchen Castle is a long, three-storey building with a four-storey residential tower at its southwest corner, topped by a gabled roof and a parapet walkway. A semicircular tower projects from the outer facade, while a stair turret on the courtyard side marks the junction between the pre-1600 section and the later Nassau-Hadamar addition. The courtyard wing has an open arcade with four round arches on Tuscan columns.

Built from 1312 under the Dillenburg line of the House of Nassau in Mengerskirchen, first mentioned in 1217; the residential tower dates to 1320 and the town received its charter in 1321. In 1341 the castle passed to Count Heinrich II of Nassau-Beilstein, under whom it was first documented and used as a widow's residence, sometimes mortgaged. From 1711 to 1806 it housed the Nassau-Dillenburg, later Nassau-Orange, office of Mengerskirchen.

The castle now serves as the town hall where local residents handle their administrative matters. Visitors can observe how the medieval structure has been adapted to serve the community's everyday needs.

The castle sits in the Westerwald region and is surrounded by numerous hiking paths that invite exploration of the landscape. Visitors should wear sturdy footwear since the area is hilly and many trails require some effort.

During the 1981–1990 renovation, restorers found remains of late Gothic frescoes inside the residential tower. The tower itself, datable to 1320, is the oldest part of the complex and was rebuilt after sections collapsed in the 19th century.