Rotunda of the Finding of the Holy Cross, Romanesque rotunda in the Old Town, Prague, Czech Republic

The Rotunda of the Finding of the Holy Cross is a small Romanesque chapel at the corner of Konviktská and Karolíny Světlé streets in Prague's Old Town. Its round nave is built of small, row-laid opuka blocks and is capped by a dome with a lantern bearing a gilded cross, a crescent and an eight-pointed star. A half-round apse with an arched frieze adjoins the east side.

The rotunda dates from after 1125 and was built on the trade route from Vyšehrad to the Vltava crossings, possibly as a private chapel of an Old Town manor. It is first documented in 1365 as a parish church. In 1784 Joseph II's reforms turned it into a warehouse; in 1860 the Art Society (Umělecká beseda) saved it from demolition and Ignác Ullmann restored the exterior.

The rotunda is used by the Old Catholic Church and belongs to the Prague Old Catholic parish, which holds regular services there. The name distinguishes it from the larger Church of the Holy Cross of the former Cyriac monastery. The neo-Romanesque fence around the plot, with Czech dog-rose motifs, was made to Josef Mánes's designs.

The chapel is located on Konviktska Street and is maintained by the Old Catholic Church of the Czech Republic. Visitors should be aware that religious services are held regularly, so opening hours may vary.

The rotunda sits at the centre of a cross formed by four early medieval churches: join St Vitus Cathedral to St Longin's Rotunda and St Clement's Church to the vanished St Philip and James Church in Smíchov, and the lines meet here. A coin of Prince Jaromír from 1012 was found nearby.