The Franciscan Monastery (Františkánský klášter) at the southern end of the old town is one of Plzeň's oldest buildings, with parts dating to the 13th century. The ensemble includes a Gothic church (Church of the Assumption of the Virgin Mary), a cloister with medieval frescoes, and the monastery buildings that today house a small museum of sacred art.
The church interior is a clean late Gothic hall with whitewashed walls and good original stone detailing. The cloister walk is the highlight — the 14th- and 15th-century fresco cycle here depicts scenes from the life of St. Francis and various Old Testament episodes, painted in an expressive style with strong red and ochre tones. The monastery museum holds vestments, chalices, and religious paintings from the region. Entry is inexpensive. The complex is easy to miss since it sits a few streets back from the main square — look for the church tower visible above the surrounding roofline.