Ubar

Ubar is a ruined city in Oman. English adventurer Ranulph Fiennes discovered the city in 1992. According to Nicolas Clapp, this probably is the lost city Iram of the Pillars the Qu'ran talks about. 
Today, ruins are left, which can be reached in a four-wheel drive. Part of the area forms the ceiling to underground vaults, which have collapsed. These vaults hold water supplies for a nearby settlement, which houses a small museum.