Saint Nicholas Cathedral (officially Cathédrale Notre-Dame-Immaculée) is the cathedral of the Roman Catholic Archdiocese of Monaco, where many of the Grimaldis were buried, including Grace Kelly and more recently, Rainier III.
The cathedral was built in 1875-1903 and consecrated in 1911, and is on the site of the first parish church in Monaco built in 1252 and dedicated to St. Nicholas. Of note are the retable (circa 1500) to the right of the transept, the Great Altar and the Episcopal throne in white Carrara marble.
Pontifical services take place on the major religious festivals such as the Feast of Sainte Dévote (27 January) and the National holiday (19 November). On feast days and during religious music concerts, one can hear the magnificent four-keyboard organ, inaugurated in 1976.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.