Tabriz is a city in northwestern Iran. It is the most populated city in the Iranian Azerbaijan region and the capital of East Azerbaijan Province. It is located at an elevation of 1, 350 meters (4, 430 feet) at the junction of the Quri River and Aji River. Tabriz has a long and rich history and was once the second largest city in Iran. It is known for its many historical monuments, including the Blue Mosque and the Tabriz Historic Bazaar Complex, which are both UNESCO World Heritage Sites.