The Blue Mosque located in Istanbul can be rightly called an architectural wonder. Commissioned to be erected in 1609 by Sultan Ahmet I, the mosque was projected to rival the Hagia Sofia with its colossal dome. This mosque attains its name from the addition of over 20,000 blue tiles. These tiles are embedded in the walls, undersides of the domes, and ceilings of the mosque. The Blue Mosque is one of the popular tourist spot, but rules of decorum must be followed while visiting since it is still in use as a mosque and must close five times a day for over one hour to devote for prayers.