LEANDRO GARCIA: Hi, my name is Leandro Garcia, I'm from Brazil, and my question is: I wonder how the Leaning Tower of Pisa is still standing.</s>THOMAS W. VENTULETT III, THOMPSON, VENTULETT, STAINBACK & ASSOCIATES: I think it's rather remarkable it's still standing, because considering the soil that it's sitting on -- it's a soft, clay kind of soil, and with the high water table that's in Pisa -- if you dug down about five feet, you'd be in water -- it's made that soil very unstable. And engineers, architects, build foundations to hold buildings up straight, and this one didn't have, really, that kind of a significant foundation. So the weak side, the south side, started to give and allowed the tower to settle some. If they had built it all at one time, it would've surely have toppled. But the fact that they built it over 200 years and compressed the soil each time, it stayed, but it leaned. And now they've excavated, through some tubes and drilling some cords, they've taken some soil out of the north side, and that's stabilizing the tower so that it actually comes back into place slightly. It's a very indiscernible amount of lean that has come back, and that will stabilize it for the next several centuries, at least.
Ask CNN: How is the Leaning Tower of Pisa Still Standing?