The Leaning Tower of Pisa was originally built as a bell tower, according to Britannica, which makes perfect sense. From atop the 183-foot-high tower, the clarion sounds of the bells could ring loud and clear across the plains surrounding Pisa. As such, the things for which the tower was built sit atop the building to this day, although as The Vintage News notes, ringing them is probably not the best idea.

Inside the tower is, actually, not much at all. As the tower’s website notes, there is “literally nothing” inside the tower; “It’s just a hollow cylinder from bottom to top.” However, that’s not entirely true as there’s a science experiment, of a sort, inside the tower, albeit an extremely minimal and simplistic one. A weighted cylinder hangs from a wire, a few feet above the heads of tourists. It serves to illustrate just how severely the tower is leaning. If the tower were perfectly perpendicular, the cylinder would hang in the middle. However, because of the building’s lean, the cylinder actually touches the interior wall, according to The Vintage News, serving as a visual demonstration of just how precarious the tower’s tilt was and is.