Saudi Arabia: Al Ahsa – Ibrahim Palace
Al Ahsa is the largest oasis in the world and is a UNESCO World Heritage site. The town existed pre-Saudi times when it was an Ottoman Empire military base, with most historic structures dating to that period. The main architectural attraction is the Ibrahim Palace aka Qasr Ibrahim, a fort built around the white-washed Ibrahim Mosque, both built in 1555. Although in town, on the outskirts is the Jawatha Mosque dating back to 629 CE, the oldest mosque on the eastern side of the Arabian peninsula. Supposedly, when the Black Stone of Kaaba was stolen from Mecca, it was kept in this mosque for 22 years.