Leaning Tower of Pisa

Construction began on 9 August 1173 on the soft clay of Piazza del Duomo. The builders laid the heavy marble foundations and reached the third tier before the ground beneath them began to swallow their work. Construction abruptly stopped. Centuries later, workers dug up a pink stone cast near the entrance bearing the name Bonanno Pisano, identifying the original architect who watched his ambitious project sink. Leaving the heavy stone to settle into the unstable earth was an accidental stroke of genius. Had the medieval masons pushed forward without a lengthy pause, the entire structure would have collapsed straight into the mud. When Giovanni di Simone resumed the project in 1275, the southward lean was obvious to everyone in Pisa. He chose to ignore the slope and attempted a clumsy architectural fix instead. He built the next three storeys at a slight angle, actively curving the masonry in the opposite direction to compensate for the sinking base. This severe overcorrection gave the campanile a distinct banana shape that remains clearly visible today. By the middle of the fourteenth century, workers finally completed the belfry and hauled seven large bronze bells to the highest floor. One of these heavy bronzes was named Giustizia, and for centuries it rang out across the city roofs specifically to announce the executions of traitors like Count Ugolino della Gherardesca. Generations of prominent engineers could not resist the urge to tamper with the tilting stone. In the nineteenth century, Alessandro Gherardesca decided to excavate around the buried base to expose the original carved steps. His workers pumped out the subterranean water they found, unwittingly accelerating the soil subsidence and worsening the steep angle. Benito Mussolini took immense personal offence at the crooked architecture in 1934, declaring the slanted landmark a national disgrace. He ordered a team to drill holes directly into the foundation and pump them full of wet cement to force the structure upright. The heavy concrete only made the tower sway dangerously from north to south before settling into an even deeper slump. By the winter of 1990, the 14,453 tonnes of marble were dangerously close to snapping altogether. The shift had reached an extreme angle of 5.5 degrees, forcing officials to lock the doors and call in a rescue committee under engineer Michele Jamiolkowski. They strapped the fragile middle tiers in steel belts and stacked a thousand tonnes of lead ingots on the northern base to act as a desperate temporary counterweight. The ultimate solution proved to be remarkably subtle. Drillers slowly removed small volumes of earth from beneath the northern edge, allowing the enormous weight of the masonry to gently sink back into a safer alignment. Today, the 296 heavily worn, sloping steps inside the marble cylinder lead straight up to the Pasquereccia bell, cast in 1262, suspended safely on a building whose historic tilt has been firmly frozen in place for at least another three centuries.