Riga Cathedral's red brick walls and black steeple dominate Old Town's central square. Built in 1211, it's famous for its size, stained glass and pipe organ, which was once the world's largest. Its Romanesque cloister is also worth a look.
The church incorporates a number of architectural styles including Romanesque, Gothic and Baroque. Access to some areas inside the cathedral is limited, so stand on one of the bridges across the Daugava River for a glorious view of the tower and the city.