The Rotunda of St Marija Assunta (sometimes shortened to as The Mosta Dome) is a church in Mosta, Malta. Built in the 19th century on the site of a previous church, it was designed by the Maltese architect Giorgio Grognet. Its dome is among the largest in the world, with a diameter of 37 meters (122ft). 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.
On April 9, 1942, during an afternoon air-raid, a 200kg Luftwaffe bomb pierced the dome (two others bounced off) and fell among a congregation of more than 300 people awaiting early evening mass. It did not explode. Its replica is now on display inside the rotunda under the words Il-Miraklu tal-Bomba, 9 ta' April 1942 (Maltese:The Bomb Miracle, April 9, 1942). One version of this event states that, upon opening the bomb, it was found to be filled with sand instead of explosive and contained a note saying "greetings from Plzeň" from the workers at Škoda Works in the German-occupied Czechoslovakia (then Protectorate of Bohemia and Moravia) who had allegedly sabotaged its production.