Osaka Castle ( or , saka-j) is a Japanese castle in Ch-ku, Osaka, Japan. The castle is one of Japan's most famous landmarks and it played a major role in the unification of Japan during the sixteenth century of the Azuchi-Momoyama period.

The siege of Osaka (大坂の役, Ōsaka no Eki, or, more commonly, 大坂の陣 Ōsaka no Jin) was a series of battles undertaken by the Japanese Tokugawa shogunate against the Toyotomi clan, and ending in that clan's destruction. Divided into two stages (winter campaign and summer campaign), and lasting from 1614 to 1615, the siege put an end to the last major armed opposition to the shogunate's establishment. The end of the conflict is sometimes called the Genna Armistice (元和偃武, Genna Enbu), because the era name was changed from Keichō to Genna immediately following the siege.