This monumental circular building (
rotunda), impressive by dimensions and by form, by the central plan of the base and by colour, that is by materialisation – brick lining – represents the return to the antique models, the beginnings of the Christianity, the patterns of early Christian and early Byzantine sacral architecture, especially to the examples from Rome, Constantinople, Thessaloniki and Ravenna (
Pantheon in Rome, the early Christian fonts or baptisteries, the Church of San Vitale in Ravenna, the Church of Sergius and Bacchus in Constantinople, the Church of Saint George in Thessaloniki), as well as to the later medieval, renaissance and baroque churches of the central type. The building has the basic form of rotunda, with an
apse in the east, the porch in the west and cylindrical
bell tower in the southeast side; it was not built according to the initial, but to the second, slightly altered project of the architect Plečnik. In the base form – along with the huge circular form with the leaning smaller circle – the symbolic reading and connection with
iconographic representation of the temple's patron holding the infant Jesus Christ. The porch with a wooden eaves is supported by three pairs of thin columns, as well as pillars of a square cross section. The columns continue in the entrance hall (
narthex), flanked by the smaller rectangular chapels. The main room is circular and cylindrical, 25 m in diameter and 17.5 m in height, with side conches, that is, the horseshoe shaped chapels in the thickness of the walls of rotunda, which are intended for special small altars and the confessional. Three conches are arranged on both north and south side, whereas opposite the entrance, in the apse, there is the main altar, that is, a deep presbytery, under which there is a crypt. The shape of rotunda is also emphasized by the specially positioned marble floor panels of different colours. Due to the large height of the church, three galleries were formed. Over the entrance there is a small gallery with the organ, the second horseshoe shaped gallery spreads all the way to the altar, whereas the upper gallery is patrol (deambulatorium), and it spreads along the entire circumference of the rotunda, thus enabling the largest penetration of natural light. Above the entrance there is a bigger oculus in the level of the first gallery. The niche in the level of the second gallery is reserved for still not realized St. Anthony's sculpture. The special attention was paid to the making of the details on the capitals of the porch and the entrance vestibule. == The interior ==