This 14th-century cathedral atop Petrov Hill was originally built on the site of a pagan temple to Venus, and has been reconstructed many times since. The highly decorated 11m-high main altar with figures of Sts Peter and Paul was carved by Viennese sculptor Josef Leimer in 1891. You can climb the tower for dramatic views.
The Renaissance Bishop's Palace (closed to the public) adjoins the cathedral. To the left is the pleasant Denisovy sady, a verdant park sweeping around Petrov Hill.