Chapel of St. Hyacinth was founded in the first half of the 14th century as part of a former Dominican monastery in which it served as a chapter house. In 1594 the chapter house was renamed to the chapel, dedicated to Saint Hyacinth Odrowąż. During the Swedish invasion in the seventeenth century, the monastic foundation was changed into barracks. Then the destruction of the town was completed by the fire of the city in 1863. The chapel was restored in 1894.
The chapel is made of brick, rectangular, two-span. Outside, the chapel is buttressed. In the eastern, southern and northern elevations, two windows are ended with a semicircular arch. The only entrance is from the west side. Inside there is a rib vault. The profile of the ribs is uncomplicated, the vaults are round, the brackets are in the form of a pyramid. There is a crypt under the chapel. It is probably the burial place of the Oświęcim lords, including prince Władysław I of Oświęcim and his wife Eufrozyna, founders of the monastery.
Website wikipedia.org, Kaplica św. Jacka w Oświęcimiu.