Construction Began on the Leaning Tower of Pisa
On this day · 9 August 1173
The builders laid the first stone in 1173, never imagining their bell tower would lean its way into history.
On 9 August 1173, masons set the first marble stone of a freestanding bell tower for Pisa’s cathedral. They intended a perfectly vertical campanile to crown the city’s wealthy maritime republic, sinking the foundation only about three metres into the soft, waterlogged ground.
That shallow footing on unstable subsoil proved fatal to the plan. By 1178, with roughly three storeys finished, the tower had already started to tilt, and work stopped for nearly a century while Pisa fought its rival cities. The long pause let the soil settle just enough to save the structure.
A flawed foundation turned an ordinary bell tower into the world’s most famous accident.
Later builders tried to correct the lean by curving the upper floors, giving the tower a subtle banana shape. The eight-storey, roughly 57-metre campanile was not completed until 1372, nearly 200 years after that first stone was laid.
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