Tower of Pisa stands at 60 metres and until 1990 was leaning at about a 10 degree angle.
Although it was designed to be perfectly vertical, it started to lean during construction.
The Flavius amphitheatre is the biggest and most imposing in the Roman world, but is also the most famous monument in Rome and is known as the "Colosseum" or "Coliseum". Started by Emperor Vespasian of the Flavia family, it was opened by his son Titus in 80 A.D.