Diego Lezama Orezzoli/Corbis

Persepolis’s main entrance, the Grand Stairway, was built by Darius’s son Xerxes (486–465 B.C.) in the northern end of the western facade. It is an elaborate double-reversing stairway-that is, staircases at both sides of the entrance rise to a landing, then switch back and rise to the platform terrace. The stairway’s steps were shallow enough to accommodate horsemen and wide enough for ten men to stand abreast. At the top of the stairway, visitors passed through the monumental Gate of All Lands.