The main building was rebuild in 1960s, by imitating the second Osaka castle built by Tokugawa. The one built by Toyotomi Hedeyoshi (豐臣秀吉)was demolished. This first picture was the water well that still existed in the first castle.
The main building was made into a museum now, with modernized internal fabric. Not a trace of history left. The theme of exhibit is about the change of regime from Toyotomi to Tokugawa and the two main battles about it, i.e. Winter war (冬之陣) and Summer war (夏之陣)