St. Longin's Rotunda, Romanesque rotunda in New Town, Prague, Czech Republic

St. Longin's Rotunda is a cylindrical chapel with a distinctive domed roof topped by a lantern, located in Prague's New Town. The stone-walled structure houses a Baroque altar dating to the 18th century within its compact interior space.

Built in the 12th century, this structure originally served as a parish church for the village of Rybníček under the dedication to Saint Stephen. Its patron saint changed to Saint Longinus following the establishment of Prague's New Town.

The rotunda is used by the Greek Catholic Church and by the Military and Hospitaller Order of St. Lazarus of Jerusalem; it is a filial church of the Greek Catholic parish of the Holy Trinity. A Greek Catholic akathist is prayed here every Monday at 8 pm, and other services are held irregularly. The annual Rotunda folk festival takes place in the adjoining area, when the rotunda can also be viewed.

The chapel is used by the Greek Catholic Church and the Military and Hospitaller Order of St. Lazarus of Jerusalem; a Greek Catholic akathist is prayed here every Monday at 8 p.m., while other services are irregular. The interior can be viewed during the annual Rotunda folk festival held in the adjacent space.

This structure nearly fell victim to demolition in the 19th century when urban construction threatened to remove it, but the historian František Palacký stepped in to advocate for its protection. His intervention saved one of Prague's rarest Romanesque buildings from disappearing from the city's landscape.