Arabia has intrigued travellers for centuries. Its vast swathes of desert were the swaddling clothes of infant Islam, the Arab race and of Arabic, a language considered holy by Muslims. It's also home to two of Islam's holiest cities and a host of modern, thriving, oil-rich metropolises. Today's Saudi Arabia has held on to its mystique by being incredibly difficult to visit. But if you can find someone to sponsor you or decide to take an expensive 'approved' tour, it's worth coming here for the desert and mountain scenery, and some of the Middle East's best archaeological sites.