These ancient Egyptian structures are dealing with erosion caused by pollution. Sewage is weakening the plates they stand on while air pollution eats away at the structures and the pollution may soon lead to their complete collapse. Because some layers are softer than others, a lot of the original detail has already been lost from erosion. While many people attribute the loss of the sphinx’s nose to Napoleon(there’s a rumor that his men shot it off), it was actually shot off by the Turks in target practice in the Turkish period.