Hegra Archaeological Site (al-Hijr / Madā ͐ in Ṣāliḥ)

South of Petra, the Nabataeans carved a second city of the dead into the desert outcrops of what is now Saudi Arabia. Hegra preserves 111 monumental tombs — 94 with sculpted façades — cut between the 1st century BCE and the 1st century CE, together with wells that reveal the builders' mastery of desert water. In 2008 it became Saudi Arabia's first UNESCO World Heritage Site, and inscriptions on its rocks reach back before the Nabataeans themselves.