How did engineers fix the Leaning Tower of Pisa? They removed soil from under its raised north side.

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Engineers saved a leaning tower by digging dirt out from under it. By 1990, the top of the Leaning Tower of Pisa hung about fifteen feet past its base. That's about the length of a car. The trouble was underneath. The tower stands on soft, wet clay and silt, and its south side had sunk deeper than its north. Engineers feared it could fall, and the tower was closed to visitors. What if they pumped cement into the foundation? Workers tried that in the nineteen-thirties. The work disturbed the ground, and the tower tipped further. What if they stacked weight on the high side? In 1993, about 600 metric tons of lead went onto the north side. It eased the lean, but a pile of lead was never meant to stay. What if they swapped that lead for hidden anchors? In 1995, crews froze the wet ground to dig them in. The freezing work sped up its southward tilt, and engineers rushed to add more lead. Some fixes made it worse. So they turned the problem around. Instead of propping up the low side, they would lower the high side. But pulling soil from under a leaning tower could tip it the wrong way. In 1998, steel cables were looped around it and anchored to the north, as a safety line. After a trial in 1999, long drills slid in at a slant beneath the raised north side. Each pass pulled out a small amount of soil, while instruments watched the tower closely. The soft ground squeezed in to close the gap left behind. The north side sank, a fraction at a time, and the whole tower rotated back toward upright. By 2001, they had pulled out about 1,340 cubic feet of soil. That's a little more than a twenty-foot shipping container holds. The top swung back about eighteen inches, roughly the length from your elbow to your fingertips. That put its lean back where it stood in eighteen thirty-eight. The tower still leans today. Now, on purpose. Would you have trusted a plan to dig underneath a leaning tower? Let me know in the comments and subscribe for a fact every day.