Achaemenian royal tombs, (from left to right, Darius I, Artazerxes and Xerxes I) set above Sasanian-era bas-reliefs, Naghsh-e Rostam. About 4.8 km northwest of Persepolis lies the imposing site of Naqsh-e Rustam in the mountain range of Husain Kuh, where Darius the Great and his successors had their monumental tombs carved into the cliff. Here in 1933 Herzfeld conducted a short survey and made soundings, but it was not until 1936 that Schmidt started to clear and document the royal tombs and to excavate the Ka'bah-i Zardusht.