The interior of the church is a mixture of Polish Gothic and impressive Polish Baroque architecture with structural features such as a large gilded Baroque high altar, a boat-shaped pulpit (1750), and the organ. The church was robbed clean and the interior utterly devastated by soldiers of the 1655 Swedish invasion (the Deluge), which explains the prevalence of Baroque in its current decoration. The church is said to contain one of the most beautiful Baroque choir stalls in Central Europe. Bartolommeo Berrecci, the Renaissance artist who designed Sigismund's Chapel at Wawel, is buried there.