At the orders of Emperor Kanmu (737-806, r. 718-806), construction of the new capital, Heian-kyo, began in 794. These green-glazed (J., ryokuyu; a type of glaze which contains lead and turns green when fired at low temperatures) tiles were produced at officially authorized tile kilns for the roofs of the major palace buildings. Some of these kilns have been discovered in Suita City, Osaka Prefecture, and Kita-ku and Sakyo-ku Wards in Kyoto City. The green-glazed tiles must have symbolized the power and glory of the new capital. Production of these tiles reached its peak in the 9th century.