If there is a final frontier of tourism left, it's Saudi Arabia. The birthplace and spiritual home of Islam, Saudi Arabia is rich in attractions and stirring symbolism. For Muslims, the cities of Mecca and Medina, rich in Prophetic significance, have no equal, while the carved temples of Madain Saleh, known as the second Petra, and the sophisticated rock art at Jubbah are the Kingdom's greatest pre-Islamic treasures.