The BBC reports that the Big Ben, at Britain’s Palace of Westminster, is leaning. The angle of tilt is calculated to be 0.26 degrees, and thus it is barely visible to the eye. By comparison, the Leaning Tower of Pisa leans at 3.99 degrees (and prior to restoration work performed between 1990 and 2001, the tower leaned at an angle of 5.5 degrees).
However, work isn’t expected to fix this Big Ben tilt until 2020. One professor estimates that it would take 10,000 years to reach the inclination of the Leaning Tower of Pisa.
Speaking of leaning towers, this is a good trivia question: which tower has the highest angle of tilt? According to Wikipedia, the answer is The Leaning Tower of Suurhusen (German: Schiefer Turm von Suurhusen), a late medieval steeple in Suurhusen, a village in the East Frisian region of northwestern Germany. The Suurhusen steeple remains the world’s most leaning tower that is unintentionally tilted, with the tower currently leaning at an angle of 5.1939 degrees (beating the world-famous Leaning Tower of Pisa by 1.22 degrees). But if I were to ask: which building/tower has the biggest tilt, regardless of it being intentional or unintentional, then the winner would be the Capital Gate tower in Abu Dhabi. Remarkably, it features an 18 degree incline.
Note: You can’t go wrong perusing Wikipedia’s list of leaning towers.