The Church of the Assumption of Our Lady, commonly known as the Rotunda of Mosta or Rotunda of St Marija Assunta (sometimes shortened to as The Mosta Dome) is a Roman Catholic church in Mosta, Malta. It is the fourth largest unsupported dome in the world and the third largest in Europe.
Built in the 19th century on the site of a previous church, it was designed by the Maltese architect Giorgio Grognet de Vassé. Its dome is among the largest in the world, with an internal diameter of 37.2 metres (122 ft); the rotunda walls are 9.1 metres (30 ft) thick (necessary to support the weight of the dome). The rotunda dome is the third-largest church dome in Europe and the ninth largest in the world.
Grongnet’s plans were based on the Pantheon in Rome. Construction began in May 1833 and was completed in the 1860s. The original church was left in place while the Rotunda was built around it, allowing the local people to have a place of worship while the new church was being built. The church was officially consecrated on the 15 of October 1871.
On April 9, 1942, during an afternoon air-raid, a SC500 kg general purpose Luftwaffe bomb pierced the dome (one 50 kg bomb bounced off) and fell among a congregation of more than 300 people awaiting early evening mass. It did not explode. The same type of bomb as pierced the dome is now on display ( the original was dumped at sea) at the back of the church in the Sacristy under the words Il-Miraklu tal-Bomba, 9 ta’ April 1942 (Maltese: The Bomb Miracle, April 9, 1942).