Saudi Arabia is divided into 13 administrative regions (or states). Saudi Arabian Cities and Towns: The map shows the location of following Saudi Arabian cities and towns: The most populous cities are: Riyadh, Jiddah, Mecca, Medina, Ta'if (At Taif), Dammam, Buraydah, and Al Khobar, part of the Dammam metropolitan area.
Because of its large area, the Kingdom has a diverse topography. The Tihama coastal plain which lies along the Red Sea, is 1,100 kilometers long, 60 kilometers wide in the south and gradually narrows to the north until it reaches the Aqaba Gulf. To the east of this plain, lies a chain of mountains called Sarawat. These mountains rise to 9,000 feet in the south and gradually fall to 3,000 feet in the north. Several large valleys slope eastward and westward from these mountains. They include Jazan valley, Najran valley, Tathleeth valley, Bisha valley, Himdh valley, Rumah valley, Yanbu valley and Fatima Valley. To the east of the chain stands the Najd Plateau which extends eastward to Samman Desert, Dahnaa Dunes and southward to Dwaser valley. This region is parallel to the Empty Quarter Desert and stretches northward to Najd plains, passing through Hail until it connects with the Great Nefud Desert, then to the borders of Iraq and Jordan. There are also some mountains in this plateau such as Twwaig, Al-Aridh, Aja and Salmah mountains.
The Empty Quarter in the south-eastern part of the Kingdom occupies an estimated area of 640,000 square kilometers composed of sand hills and lava fields.