The Blue Mosque in Istanbul, Turkey was commissioned by Sultan Ahmed I in 1609 and completed in 1616. It was built on the site of the Byzantine imperial palace and hippodrome facing Hagia Sophia, combining Ottoman and Byzantine architectural styles. The mosque interior features over 20,000 handmade ceramic tiles and has a large central dome surrounded by four smaller domes and six minarets. It was the last great mosque of the classical period of the Ottoman Empire and remains one of the most impressive monuments in Istanbul.