The Tower of Pisa, the LEANING Tower of Pisa, is a free-standing campanile (bell tower) in the Piazza dei Miracoli (Square of Miracles) of this former medieval city-state. It’s defect, a prominent tilt to one side, is world famous.
Built in three construction phases between 1173-1372, the massive wedding cake-like tower, when completed, tilted at a 5.5 degree angle, but late 20th-early 21st century ingenuity righted the eight-story landmark to only a 3.97 degree angle.
So, why does the torre pendente, as local pisani call her, lean? Well, the problem wasn’t created up on the drawing board, but underneath, where the Tuscan sun doesn’t shine, as the tower’s foundation was built on very soft silty soil that had difficulty supporting the 14,500 ton, bright-white marble tower. It wasn’t until the second tier was completed that the lean became noticeable, and it only worsened as the tower slowly grew.
Had I been on site — I wasn’t born yet — I would’ve called the shift supervisor over to point out the flaw.
Me: Hey boss, I think this baby is leaning.
Shift supervisor: Keep your piehole shut, we’ve got a deadline to meet.
One year shy of 200-years in the making, it’s unclear who the original designer was, but during the three phases of construction — all interrupted due to wars involving the former maritime republic — at least five prominent Italian architects took part in trying to straighten the 56.67 m (185.93 ft.) tall Romanesque tower as it continued to tilt with each new tier.
The “Big Lean” remained an 800-year-old mystery until John Burland, an English geotechnical engineer and renowned soil mechanics expert, arrived on the scene in 2003 and discovered the cause: a fluctuating underground water table that perched higher on the tower’s north side, causing the tower’s characteristic slant to the south.
Burland, now Professor Emeritus and Senior Research Investigator at the Department of Civil and Environmental Engineering of Imperial College London, introduced a new drainage system beneath the north side of the square allowing the water underneath to flow away from the tower’s base. Problem solved.
For his efforts in preventing the Leaning Tower of Pisa, one of the jewels of this UNESCO World Heritage site, from toppling over, Prof. Burland was awarded the Knight Commander of the Royal Order of Francis I by the Duke of Castro.
The Leaning Tower is undoubtedly Pisa’s most recognizable image and one of its main attractions. Despite its prominent 17 feet off vertical tilt, it’s still standing after all these years.
Feel free to climb the spiral staircase of 297 steps up to where the tower’s seven bells hang.
Don’t worry, it’s safe.
Isn’t that right, Prof. Burland?
©The Palladian Traveler