Osaka Castle is also famous to some for its incredibly well-built stone wall, which is impressive in its sheer size, with an estimated 500,000 to 1 million large stones (up to 12kg) having been used in its construction. The moat walls stand at up to 20 metres tall and 90 metres wide.

Osaka Castle is special because it serves as a powerful symbol of the unification of Japan. Originally built in 1583 by the warlord Toyotomi Hideyoshi, it was designed to be the largest and most formidable fortress in the country, intended to intimidate rivals and showcase the power of the Toyotomi clan. Its architecture is a marvel of "burdock piling," featuring sheer stone walls up to 20 meters high and massive moats that proved nearly impenetrable during the Siege of Osaka in 1614. While the current main keep is a 1931 concrete reconstruction (further renovated in 1997), it is a faithful aesthetic replica of the Edo-period design, adorned with gold leaf and "shachihoko" (mythical tiger-headed fish) roof ornaments believed to protect against fire. The castle grounds are also a world-renowned "Hanami" (cherry blossom viewing) spot, home to over 600 cherry trees. It acts as a bridge between Japan's samurai past and its modern identity, housing a high-tech museum that details the life of Hideyoshi and the turbulent transition into the peaceful Edo era.