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 ancient Argos Theater was built in 320 BC. and is located in Argos, Greece against Larissa Hill. Nearby from this site is Agora, Roman Odeon, and the Baths of Argos. The theater is one of the largest architectural developments in Greece and was renovated in ca 120 AD.
The Hellenistic theater at Argos is cut into the hillside of the Larisa, with 90 steps up a steep incline, forming a narrow rectilinear cavea. Among the largest theaters in Greece, it held about 20,000 spectators and is divided by two landings into three horizontal sections. Staircases further divide the cavea into four cunei, corresponding to the tribes of Argos A high wall was erected to prevent unauthorized access into the theatron and may have helped the acoustics, but it is said the sound quality is still very good today.
Around 120 CE, both theaters were renovated in the Roman style.