We don't know why just Dahshur was the favourite place of Sneferu, but he wanted his tomb right there, several kilometers to the south from Saqqara. This pyramid is called Bent pyramid and it was the very first non-level pyramid. The angle inclination of the walls changes steeply around the half of its height.
Original inclination was too steep (over 58°), probably because of not enough solid subsoil, which was not solid rock. The builders decided to change the inclination and decrease the arch load because of walls dismounting and cracks in the upper chamber, which appeared inspite of struts. So the inclination changed to 43°22' at an approximate height of 50 meters above the ground.
Even then the pyramid didn't seem safe to Sneferu's advisers. According to time data the finishing work on Bent pyramid ran at the same time as the start of Meidum pyramid alterations. The final decision was to begin with the third pyramid construction, approximately 2 kilometers to the north from Bent pyramid.
The builder preserved the inclination of 43°22' this time and constructed the first genuine pyramid with smooth walls, which was a predecessor of great pyramids in Giza. White limestone used for facing the pyramid disappeared as time went on and reddish stone appeared, that originated from a nearby quarry. That's why this pyramid is called Red pyramid. Sneferu was buried in this pyramid in the end.