The Hoober Stand was built in the mid 18th century to honor Thomas Watson Wentworth, who fought alongside King George II in the Jacobite Rebellion.
Although it looks relatively plain from the outside, the stand is in the shape of a tapering pyramid with a hexagonal lantern on top. The tower's angles not only create the illusion that it's toppling over, but they also make it seem like the lantern moves depending on where it's viewed from.
For example, in the photo above, the lantern looks like it's situated to the left of the tower's center, even though it sits squarely in the middle.