Toyotomi Hideyoshi built Osaka-jo in 1583. Hideyoshi, being the great battle expert he was, designed the most formidable castle ever built in Japan. One large moat surrounded the whole castle with only two ways across it. One of those was a small bridge that could be easily defended or even destroyed if necessary. The inner grounds which contained the large donjon were actually built 3 levels above the water level of the moat. Any attacker would have to scale three high stone walls and climb over 3 sets of turrets to get to the inner grounds.

Of course no castle is invincible and in 1615 it fell to the Tokugawa forces. Hideyoshi's heir, Hideyori, committed suiced before being captured. In 1620 Tokugawa completely renovated the entire castle and built a new donjon making the whole castle even bigger and grander than Hideyoshi's original. In 1665 the donjon was struck by lightning and burned to the ground. It was never rebuilt.