Estonia's answer to the Leaning Tower of Pisa is the so-called 'Leaning House' at the northeast corner of Town Hall Square. Builders in the 1790s unwisely set part of its foundation on the old city wall and another part on wooden piles. The latter eventually sank, giving the house a noticeable lean. It was in danger of falling over until Polish engineers managed to shore it up during the Soviet period. You can see the inside of the house by visiting the Tartu Art Museum.