One of Italy's signature sights, the Torre Pendente truly lives up to its name, leaning a startling 3.9 degrees off the vertical. The 56m-high tower, officially the Duomo's campanile (bell tower), took almost 200 years to build, but was already listing when it was unveiled in 1372. Over time, the tilt, caused by a layer of weak subsoil, steadily worsened until it was finally halted by a major stabilisation project in the 1990s.
Building began in 1173 under the supervision of architect Bonanno Pisano, but his plans came a cropper almost immediately. Only three of the tower's seven tiers had been built when he was forced to abandon construction after it started leaning. Work resumed in 1272, with artisans and masons attempting to bolster the foundations but failing miserably. They kept going, though, compensating for the lean by gradually building straight up from the lower storeys. But once again work had to be suspended – this time due to war – and construction wasn't completed until the second half of the 14th century.
Over the next 600 years, the tower continued to tilt at an estimated 1mm per year. By 1993 it stood 4.47m out of plumb, more than 5 degrees from the vertical. To counter this, steel braces were slung around the third storey and joined to steel cables attached to neighbouring buildings. This held the tower in place as engineers began gingerly removing soil from below the northern foundations. After some 70 tonnes of earth had been extracted from the northern side, the tower sank to its 18th-century level and, in the process, rectified the lean by 43.8cm. Experts believe that this will guarantee the tower's future for the next three centuries.
Access to the Leaning Tower is limited to 40 people at a time – children under eight are not allowed in/up and those aged eight to 10 years must hold an adult's hand. To avoid disappointment, book in advance online or go straight to a ticket office when you arrive in Pisa to book a slot for later in the day. Visits last 35 minutes and involve a steep climb up 251 occasionally slippery steps. All bags, handbags included, must be deposited at the free left-luggage desk next to the central ticket office – cameras are about the only thing you can take up.