See the TOWER of PISA

The Leaning Tower of Pisa is a bell tower in Pisa, Italy, famous for its drastic lean to one side. The bell tower is part of Pisa's Cathedral Square, and is situated next to the Duomo (Cathedral) of Pisa. The bell tower, or campanile, is tilted about 3.99 degrees to one side, although before it was restored it leaned up to 5.5 degrees. The restoration project lasted from 1990 to 2001, and helped to prevent the tower from leaning too far and collapsing.

The campanile was constructed alongside the cathedral beginning on August 14, 1173, while Pisa was still an autonomous republic. The tower began to lean even during construction, after the first three stories were built, because of the soft and unstable soils it was built upon. Construction was halted for some time, but resumed in 1272, while builders attempted to counteract the tilt by altering construction. The construction paused again after 1284 because of battles between Pisa and Genoa. The tower was finally completed in 1372, after almost 200 years of off-and-on construction. The tilt became more extreme over time, until restoration stabilized it.

Original plans for the design of the tower have been attributed to Guglielmo and Bonanno Pisano, but it may have been Diotisalvi who was the actual architect for the Tower of Pisa.
The tower stands about 56 meters (183 feet) high, with eight stories. Inside the tower there are seven bells and 296 steps to the top.
Visitors to the Leaning Tower of Pisa can climb these towers and have their photo taken in the classic pose of holding the tower up (or knocking it down).
Source: mapsofworld.com