The pyramids at Dahshur, about 40 kilometres south of Cairo, are less famous than Giza but in some ways more interesting — they represent the experimental phase of pyramid building, when Egyptian architects were still working out how to build reliably. The two main pyramids here are the Bent Pyramid and the Red Pyramid, both built by Sneferu, father of the Great Pyramid's builder Khufu.
The Red Pyramid is the first true smooth-sided pyramid — it was built after the Bent Pyramid's angle was corrected, and it worked. Visitors can descend into the interior, a long, steep passage into a series of corbelled chambers with a distinctive smell of ancient stone. The site is far less visited than Giza, and on a weekday morning you may have it almost to yourself.