The Royal Chapel (Kaplica Królewska) was built by Jan III Sobieski as a place of
worship for Catholics of the parish of St Mary’s, which had become a Protestant
church in 1529. The chapel was built in 1678–81 to designs by the great royal
architect Tylman van Gameren.

The carving in the Kaplica Królewska is by Andreas Schlüter the Younger. The
chapel itself is enclosed within a chamber and is situated on a raised floor.
The interior is less ostentatious than the façade.