St. Peter's Parish Church is one of the oldest churches in Ljubljana. The original church at the site was presumably built near the city walls already at the turn of the 9th century on the order of Paulinus II, the Patriarch of Aquilea. It was the seat of the Primitive Parish of Ljubljana. The church was encircled by a cemetery that was the main town cemetery until 1779, when it was abandoned.
The current building was erected in a Baroque style between 1730 and 1733 upon the plans of the architect Carlo Martinuzzi, who based them upon the Church of San Giorgio Maggiore in Venice. The model of the church was made by Giovanni Fusconi, who also gave some technical advice. The church was built by the master builder Gregor Maček, Jr. Interior division of the church has been preserved from the period.
After the Ljubljana earthquake of 1895, the church was renovated by the architect Raimund Jeblinger in a neo-baroque style. This renovation was strongly criticised for its supposed low quality, and was followed by another, done between 1938 and 1940. The façade was completely remodeled by the architect Ivan Vurnik, while his wife Helena Vurnik contributed new interior decorations and mosaics. The church's ceiling frescoes are the work of baroque painter Fran Jelovšek; altar paintings are by Valentin Metzinger.
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.