The Bent Pyramid of Dahshur is located south of Cairo. It is one of the unusual pyramids of ancient Egypt, but until 1996 it was relatively unknown outside archaeological circles because there was an army camp nearby and so the area was restricted.
The Dahshur Pyramid originally began with a very steep angle of 54 degrees but halfway through construction the builders realized that the angle was too steep. So the upper half was completed at a shallower angle of 43-degrees to prevent the structure from collapsing. This gives the Pyramid a 'bent' appearance leading to its modern name.