The Leaning Tower of Pisa has long been hailed as a medieval engineering marvel. The tower’s iconic tilt has attracted tourists from all over the world and the Italian government even enlisted engineers to fix the tilt of the tower. Have you ever wondered how this tower was built?

The city of Pisa actually gets its name from the Greek word for “marshy land” which is an apt description of the clay, mud, and wet soil found underneath the city’s surface. Ancient Romans sought to counteract this problem by building foundational supports called piles. Piles were like pillars underneath the ground, and their bases rested on the bedrock underneath the surface. Engineers thought that the piles only needed to be 3 meters tall (around 10 feet tall) to support the tower and prevent the marshy ground from destabilizing it.

Less than five years after the base of the tower had been built, one side of the base was already sinking into the ground. This sinking structure is detrimental to the tower’s integrity; worker’s adding more weight and building higher stories would cause the tower to sink further into the ground, potentially risking the lives of all who entered. War caused workers to temporarily abandon construction, and this break allowed the ground to settle a bit, creating a better foundation. To compensate for the tilt, architects made the stories lopsided so the tower would appear to be straight. Unfortunately, this caused the tower to tilt further.