Dadan is considered among the most important discoveries in the Al-Ula desert. It was the capital of the kingdoms of Dadan and Lehyan. It was built precisely of stone, overlooking the valley oasis, and dates back to between the late ninth and early eighth centuries BC (Dadan Kingdom) and between the fifth centuries. And the second BC (Kingdom of Lihyan). More than a dozen tombs cut into a red cliff can be explored and look like simple dark rectangles from afar.