Petra

Petra was the capital of the Nabataean Kingdom, an Arab trading people who controlled the incense and spice routes of the ancient Near East from roughly the 4th century BCE. The city's most iconic structure, Al-Khazneh ("the Treasury"), is a 40-metre-high façade carved directly into a sandstone cliff face, reached by walking through the Siq — a narrow natural gorge over a kilometre long and in places only a few metres wide, whose walls rise up to 80 metres on either side. The Nabataeans engineered an extensive system of dams, cisterns, and ceramic pipes to capture seasonal flash floods and supply the city with water in an otherwise arid environment.

After a series of earthquakes, most severely in 363 CE, and a shift in trade routes toward sea-based commerce, Petra was gradually abandoned and largely forgotten by the Western world, known only to local Bedouin. It was "rediscovered" for European scholarship in 1812 by the Swiss explorer Johann Ludwig Burckhardt, who disguised himself as a Muslim traveller to gain access to the site. Archaeological work continues to reveal new structures — ground-penetrating radar surveys in 2016 identified a previously unknown monumental platform near the city centre — and an estimated 80% of the city, including most of its residential areas, remains unexcavated.