Madain Saleh is the most iconic historical site of the Kingdom of Saudi Arabia and the first to be listed as a UNESCO Word Heritage, back in 2008. It is located in the north of Madinah Province, in the area of Al-Ula, where many other fascinating archeological sites attest to the thousands of years of human occupation of the area thanks to the underground water available for millennia.
Madain Saleh means the "cities of Saleh" after the name of the Prophet Saleh who tried to convert the ancient people of Thamud to Islam. But this name started to be used only during the Ottoman occupation of the Hejaz, whereas the people who built this city, the Nabateans, called it Hijra (as it appears in some ancient inscriptions at the site), and the Romans used to call it Hegra. The historical site is still known today in Arabic as Al-Hijr, after which a Surat of the Holy Quran is named.