Cal and Virginia Ann on the blocks of the Bent Pyramid. The Bent Pyramid (2613-2589 BC), built under the rule of King Sneferu. The Bent Pyramid was the first attempt at building a smooth sided pyramid, but proved to be an unsuccessful build. This was due to the miscalculations made on the structural weight being placed on the soft ground of sand, gravel, and clay, which tended to subside.