A Baroque collegiate church dominating the old market square, built in the 17th century on the site of an earlier Gothic church. The interior is richly decorated with frescoes, gilded altarpieces, and the tombs of the Archbishops of Gniezno — Łowicz was the seat of the Polish primates for centuries, and the church reflects that long ecclesiastical importance.
The church is the focal point of the Corpus Christi procession each spring, when the entire floor of the square in front of it is carpeted with flower-petal designs and locals process in full traditional costume. At any time of year, the Baroque interior is well worth a look.