The Cathedral of St Nicholas stands at the corner of the main square and has been the dominant church of České Budějovice since the 13th century. The current baroque building dates from a major reconstruction in the early 18th century. The interior is light and airy — pale plasterwork, frescoed vaulting, and ornate side chapels that reward a slow wander.
The cathedral is connected to the Black Tower by a covered passage that runs across the street at upper-floor level — an arrangement that dates from the original medieval complex. The church is free to enter and open most of the day. Evening mass draws a regular congregation, and the organ concerts held here occasionally are worth catching if you are in town.