The old church of the Bridgettine Order - of the Assumption of the Blessed Virgin Mary the Victorious - was built between 1412-1426 in the place of a chapel, dating from 1396, for the Bridgettine sisters and brothers brought over from Gdańsk in 1426. The church and monastery/convent were financed by King Władysław Jagiełło as a thanksgiving offering for the victory achieved during the Battle of Grunwald. The church was constructed in the Gothic style. Its unique feature is the asymmetric division of its interior into two naves. Originally, the interior was decorated with wall paintings and covered with a flat ceiling, which was replaced with a Gothic rib vault around the mid-16th century. The vault over the presbytery has early-Baroque decorations dating back to the days of the Abbess Dorota Firlejówna (1631-1660). The tower was erected in the 1st half of the 16th century and heightened at the end of the 16th century or at the dawn of the 17th century. Among the old interior furnishings, it is worth paying attention to: the Gothic painting of St Bridget of Sweden from the 15th century at the main altar of the presbytery painted on a plank (part of an old triptych), paintings in stalls depicting scenes from the life of St Bridget created by Jan Szretter from the 2nd quarter of the 17th century, and emblematic paintings on the benches. Above the vault of the main nave (in the attic), sections of a Gothic painting ornament, probably from 1460-1470, have been preserved. The polychrome was originally below the vault covering the nave. One of the sections depict a march of knights under the command of the King with the city in the background, assisted by townspeople on horses, and is considered one of the earliest paintings in Poland depicting secular themes.