The history of the Basilica of St. Ägidius in Mittelheim is extremely diverse. Next to the abbey church of Eberbach, it is the oldest church in the Rheingau. The Romanesque building dates back to the 12th century. The foundations of the south side stand on the remains of a predecessor building, an Ottonian chapel from the 10th century.

The former monastery church served as a place of worship for the Mittelheim parish since 1263 at the latest, but it was not until the middle of the 14th century that it also received its own parish priest. With only minor changes, the Romanesque building has survived the centuries. In the 20th century the basilica was renovated again in the original style.

Especially worth seeing are the wood-carved pulpit from 1511, the baptistery from the 15th century and the numerous statues and gravestones.