The belltower in Piazza del Duomo is known worldwide as the 'leaning tower' and it is undoubtedly the symbol of Pisa. Work began in 1173 and was interrupted due to subsidence, which is the reason for the inclination. Work began again in 1275 and the tower was completed in the mid-fourteenth century. 294 steps lead to the top of the tower, where Galileo Galilei carried out experiments on the force of gravity. Even today Pisa is a cultural city and home to the prestigious university 'Scuola Normale Superiore'.