The Tallinn City Hall or square that dominates Tallinn's main square dates back to the Middle Ages. It was built between 1402-1404 as a meeting place for the men of the ruling guilds and has been a masterpiece in the city ever since. Nowadays the town hall is used mainly for concerts or to entertain visiting kings or presidents. It opens its doors in July and August to visitors as a museum. The building's interior is impressive, with colorful meeting rooms, vaulted ceilings, intricate wood carvings, and some of the city's most valuable art treasures, including the carved Tristan and Isolde benches.