It is an easily recognizable landmark of the city with its green dome and twin towers and stands at Cyril and Methodius Square (Ciril-Metodov trg) by the nearby Ljubljana Central Market and Town Hall.

[3] In 1700, at the initiative of Dean Johann Gregor Thalnitscher (Dolničar) and the Academia Operosorum Labacensium, the Capuchin friar Florentianus Ponnensis from Milan or Bologna designed a new Baroque hall church.

[4] The following year, after the construction already started, the plan was revised and complemented by the Jesuit architect Andrea Pozzo who designed it as a basilica and added to it a dome.

The dome with a cupola that replaced a painted one in 1841, was built by Matej Medved, whereas carpenter works were carried out by Jurij Pajk [sl].

A sundial with Roman numerals and a Latin motto (Nescitis diem neque horam – "You don't know the day or the hour"), dated to 1826, also decorates the southern facade.

The entrances have bronze sculptured doors from 1996, created at the 1250s anniversary of Christianity in the Slovenian territory and the visit of Pope John Paul II.

Other notable decorations in the cathedral include the altar angels by the brothers Paolo and Giuseppe Groppelli on the right part of the nave (1711) and by Francesco Robba on the left (1745–1750).

Angelo Putti created the statues of the four bishops of Emona seated under the dome beam (1712–1713), the bust of Johann Anton Thalnitscher [sl] (1715), and the reliefs of angels in the spherical triangles at the altar of the Holy Trinity.