Also called the Belltower of Pisa and the Tower of Pisa, the Leaning Tower of Pisa stands in the Piazza dei Miracoli (Square of Miracles) next to the Cathedral of Pisa in Pisa, Italy, about 50 miles west of Florence. According to a 2013 National Geographic article, with current restoration efforts and new technologies, the Tower may remain standing for at least another 200 years.
Because Pisa is built on marshy ground, the Leaning Tower of Pisa started to lean almost as soon as construction began in 1173. Because of the weight of the marble, by 1178, when builders started work on the third floor, the lean was already noticeable. According to a Tower of Pisa website, despite architects’ and engineers’ best efforts to correct the lean over the next 226 years, it was clear that the Tower was falling at the rate of 1 to 2 millimeters per year. As of 2014, the Leaning Tower of Pisa leans at 3.99 degrees. Physicists calculate the maximum angle that the Tower can lean without falling to be 5.44 degrees, although at its most severe angle, the Tower leaned at 5.5 degrees. Originally approximately 197 feet tall, the Leaning Tower of Pisa stands at about 185 feet and weighs around 14,500 tons.