This is perhaps the only round Catholic church in Lithuania (a domed rotunda). It is a valuable architectural monument and a fine example of a Classicist rotunda. The church was designed by the architect Laurynas Stuoka-Gucevičius shortly before his death. Construction was supervised by the Dominican Laurynas Bortkovičius. During construction (1803–1822) the original design was slightly altered. The brick, plastered walls are covered by a slightly flattened domed roof. The octagonal lantern crowning the dome was added later. On the east side the building is adorned with a six-column portico in the Doric style, in whose niches once stood large (2.75 m high) statues of the four Evangelists – St Matthew, St Luke, St Mark and St John – and of the Apostles St Peter and St Paul. Worth noting is the original holy-water stoup by the side doors of the church, showing St John the Baptist standing beside an angel holding a basin for holy water. It is also worth paying attention to the building's acoustics, which reveal themselves when you climb the stairs cut into the walls up to the dome. In 1902 a group of artists from Tyrol worked in the church. They painted pictures for the altars and wall compositions. The decoration of the vaults and the scene of the Coronation of the Mother of God in the centre of the dome are also the work of the Tyroleans. The same artists painted the fresco of the main altar. It shows God the Father seated, his head adorned with a triangular halo. In his left hand he holds a sceptre, and his right is raised towards a dove in flight. Jesus Christ, seated beside him, looks down, and his outstretched arms seem to invite everyone into his embrace. Two more painted scenes are by the main doors of the church. One shows St Stanislaus, the other St Anthony of Padua. On the main altar, above the lower altar (modelled on the Gate of Dawn in Vilnius), stands a second altar dedicated to the Mother of God, decorated with figures of St Joachim and St Anne. Two angels kneel by the tabernacle as if on guard. The side altars are decorated with high-relief carvings. One shows the Mother of God giving the rosary to St Dominic and St Catherine. The other shows the suffering Christ on the cross, with the Mother of God and the Apostle St John standing beside him.