The Dome Cathedral (Rīgas Doms) is the largest church in the Baltic states and the oldest building in Riga, begun in 1211 by Bishop Albert who founded the city. Its architecture is a layered record of eight centuries of building — Romanesque foundations, a Gothic nave, Baroque additions — all accumulated without anyone quite agreeing on a single style.
The interior is worth visiting chiefly for two things: the cloister, which houses a small lapidary museum of medieval stonework, and the great organ, one of the finest in Europe with over 6,700 pipes. The cathedral hosts organ concerts throughout the year; if you can catch one, do. The acoustics are extraordinary.
The Dome Square (Doma laukums) in front is the social centre of the Old Town — ringed with restaurant terraces in summer and a Christmas market in December.