The square Campo dei Miracoli (Field of Miracles) is flanked by Pisa's most famous monuments, the Duomo, the Baptistery (famous for its incredible acoustics), the Camposanto cemetery (known as 'the most beautiful cemetery in the world') and the iconic leaning Tower. The latter is in fact the Cathedral's campanile (bell tower) - construction began in 1173 and the original architect remains unknown. The famous story of Galileo dropping canon balls off the tower as part of his experiments, is unfortunately widely considered to be a myth.
The Museo Nazionale di S. Matteo, located in a Benedictine monastery, houses sculptures and paintings from the 12th - 15th centuries, including works by Pisano and Masaccio.
Pisa isn't just about ancient art; American artist Keith Haring painted a gigantic (180m square!) mural on the south wall of the Church of S. Antonio, entitled "Tuttomondo". Each figure in the work represents a different aspect of peace in the world.