Osaka Castle (Osaka-jo) was built by the hegemon Toyotomi Hideyoshi, who ruled Japan in the latter half of the 16th century, on the site of a temple called Ishiyama Hongan-ji. The construction work began in 1583 and most buildings such as the castle tower were completed in 1585. Its gross area is over 3,300,000 sq m and tens of thousands of people were daily mobilized in its construction. The donjon is five-tiered and nine-storied, and has large golden sea creature ornaments shining on the rooftop. It is claimed that pure gold chasings were set in the corridors. One of the charms of this castle is the beauty of its stone wall. Reportedly, there are 40,000 rocks in the wall. Legend has it that powerful daimyo from all parts of Japan competed in carrying the large rocks to display their loyalty to the Toyotomi hegemon. The existing castle tower was built in 1931. It has five tiers and is approximately 40 m high. It is the symbol of Osaka.