The Church of the Assumption of Our Lady, commonly known as the Rotunda of Mosta, is the third 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. the rotunda walls are 9.1 metres 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 World War II air-raid, a 500 kg Luftwaffe bomb pierced the dome 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.
References:The Cathedral of Saint Mary Major, often called Lisbon Cathedral or simply the Sé, is a Roman Catholic cathedral located in Lisbon, Portugal. The oldest church in the city, it is the seat of the Patriarchate of Lisbon. The cathedral has survived many earthquakes and has been modified, renovated and restored several times. It is nowadays a mix of different architectural styles.
The site where it stands was the principal mosque of Lisbon when it was an Arab settlement. The construction of the cathedral started around 1150, three years after the city was conquered from the Moors during the Second Crusade. Shortly after the victory the English knight Gilbert of Hastings was named bishop of the city of Lisbon.
One good reason to visit the Cathedral is to visit its charming cloisters located in the back. There are several tombs in the cathedral, the most notable of which is the beautifully sculpted tomb of Lopo Fernandes Pacheco and his wife.