Madain Saleh (مدائن صالح , also Medain Saleh) is a large archaeological site in Saudi Arabia.
A Nabataean city hewed out of rock in the same style as Jordan's far more famous Petra, Madain Saleh is on UNESCO's tentative list for World Heritage inclusion  and would be a top tourist draw in any other country than Saudi Arabia. As it is, though, access to the site is fairly difficult and many Muslims refuse to enter the area due to a section in the Qur'an (Al-Hijr 15:80) often interpreted as a curse against it.
A 100 Riyal permit is necessary for visiting Madain Saleh. Tour operators or hotels will usually arrange these on your behalf (apply at least one week in advance), or do it yourself at the National Museum in Riyadh.
The nearest airports are in Al Wajh (220 km) and Medina (300 km, and yes, the airport is open to non-Muslims). Until 2004, visitors usually traveled via Hail (400 km), but a new road from Al Wajh now makes that route considerably faster.
Facilities all set up and ready for tourists (as of 2000 anyway), but LOCKED tight as a drum! Travel around inside as much as possible, there are many little interesting things to see. Use of steel sleepers stolen from the railway for all sorts of agricultural uses, and so on.
During your visit to Madain Saleh Area , you can eat good food in your hotel , (ARAC Al-Ula Hotel 4+ stars or Madain Saleh Hotel also 4 stars category), both hotels offer good and clean food , also if you want to try the local food you can visit to nice and clean resturants in the city of Al-Ula. your tour guide should guide you to the best places to eat.
Staying overnight at Madain Saleh is not allowed, so most visitors use one of the two hotels in Al-Ula.
You can, if so equipped, camp quite close to the gates of Medain Saleh quite readily. There are organised tours which set up outdoor camps in a very luxurious fashion near the entrance.