The Sultan Ahmed Mosque is an historical mosque in Istanbul. The mosque is popularly known as the Blue Mosque for the blue tiles adorning the walls of its interior. It was built from 1609 to 1616, during the rule of Ahmed I. Like many other mosques, it also comprises a tomb of the founder, a madrasah and a hospice. While still used as a mosque, the Sultan Ahmed Mosque has also become a popular tourist attraction.
At its lower levels and at every pier, the interior of the mosque is lined with more than 20,000 handmade ceramic tiles, made at Iznik (the ancient Nicaea) in more than fifty different tulip designs. The tiles at lower levels are traditional in design, while at gallery level their design becomes flamboyant with representations of flowers, fruit and cypresses. More than 20,000 tiles were made under the supervision of the Iznik master potter Kasap Haci and Baris Efendi from Avanos (Cappadocia). The price to be paid for each tile was fixed by the sultan's decree, while tile prices in general increased over time. As a result, the quality of the tiles used in the building decreased gradually. Their colours have faded and changed (red turning into brown and green into blue, mottled whites) and the glazes have dulled. The tiles on the back balcony wall are recycled tiles from the harem in the Topkapı Palace, when it was damaged by fire in 1574.