Mosta boasts the third largest unsupported dome in the World dedicated to the Assumption. The Feast of the Assumption is held on August 15 and it is a public holiday. The church is also known as the Rotunda of St Marija Assunta. On 9 April 1942, the church was nearly destroyed during World War II. An Axis bomb hit the dome of the church but failed to explode. The detonator was removed and a replica bomb is now displayed as a memorial.
The Rotunda was designed by George Grognet de Vasse, a French citizen resident in Mosta. Mosta residents, at that time totalling not more than 1500, built the church. It took them 27 years to complete but the result is a tourist attraction of world standard. Grognet chose the type of stone by insisting on having one slab from each quarry operating in the Islands. He then proceeded to test their durability. In the end he chose a quarry in Mosta near to Ta' Vnezja, at the gate of an old military airfield.