Naqsh-e Rostam where the tombs of 4 ancient emperors have been hewn out of the rock. There are 4 tombs (Darius I and II, Xerxes and Artaxerxes) cut out of the cliff way above the ground, each tomb has impressive stone reliefs engraved below it. As the kings at that time were Zoroastrian, their bodies were initially put on Towers of Silence to be picked clean by birds of prey, after that the bones were moved into the rock tombs.