In the mid-16th century, after Japan was unified by the development of the market economy, the building reached a new level. The historic Osaka Castle, built in 1586 by Toyoson Sioji, is made of majestic stone walls. The main building of Osaka Castle stands in the center of Osaka Castle Park, the grandiose, bronze-plated, and spectacular. During the feudal civil war in Japan, various feudal lords built the Acropolis on the small high hills of the city. A high city in the center of the Acropolis was originally a mansion called Tianshou Pavilion.