The siege

Toyotomi Hideyoshi built the original castle from 1583 as the seat of the man who had unified Japan. It was the largest fortress in the country, with concentric moats and outer defences on a scale nothing else matched.

The winter siege, and the trick

In the winter of 1614 Ieyasu besieged it and could not take it. So he negotiated: peace, on the condition that the outer moat be filled in as a gesture of good faith.

His men filled the outer moat. Then they kept going and filled the inner one too. When the Toyotomi protested, Ieyasu expressed regret at the misunderstanding, and in the summer of 1615 attacked a castle that no longer had its defences.

The castle fell, Hideyoshi’s heir and his mother died inside it, and the Toyotomi line ended. Japan then had no major battle until the 1860s.

What you are looking at

Ieyasu rebuilt the castle in the 1620s — bigger, and deliberately on top of the Toyotomi ruins, so that nothing of Hideyoshi remained visible. The stones were brought by sea from across western Japan; the largest, at the Sakuramon gate, is estimated at well over a hundred tonnes.

Lightning burned that keep in 1665 and it was not rebuilt for 266 years. The tower you climb is from 1931, funded by public subscription from Osaka citizens, built in reinforced concrete, and restored in 1997. It has a lift.

So: the keep is a twentieth-century museum, the walls are seventeenth-century Tokugawa, and Hideyoshi’s original is underneath, excavated in places and visible in one preserved section.