There are many symbols of Italy—gondolas, Sophia Loren, gelato—but none is more iconic than the Leaning Tower of Pisa. I’ve always thought it strange that an engineering screw-up based on poor planning and shoddy construction has become one of the Seven Wonders of the World.

Our question in Italy: Will it lean forever, or will it eventually fall? Over a couple Italian beers, we plotted the physics.

The tower was built back in 1173 with marble, so the assumptions of modern engineering don’t really apply. Not long after it was built, the ground under one side started to sink under the weight of the stones. Workers tried to compensate by making the columns on the other side slightly bigger to even