Roof architecture at Casa Batllo; Part of the Illa de la Discordia, Eixample District, Barcelona, Spain. Originally built in the building was restored by Antoni Gaudi and Josep Maria Jujol, (wikipedia) // photo by
Blue Mosque or The Sultan Ahmed Mosque is an historic 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 during the rule of Ahmed I.