A short history
The original castle was built in 1583 by Toyotomi Hideyoshi, one of the key unifiers of feudal Japan, on the site of a former temple stronghold. It was destroyed and rebuilt more than once over the following centuries under Tokugawa rule, before the current concrete tower was completed in 1931 as a reconstruction, and later restored again in the 1990s.
What's inside today
The tower now houses a museum covering the castle's history and Hideyoshi's life, with displays across several floors and an observation level near the top looking out over the surrounding park and city. It's a manageable, well-organised visit rather than a sprawling one — most people are through in an hour or two.
The park is arguably the main event
Osaka Castle Park's moats, stone walls and grounds are free to walk regardless of whether you pay to enter the tower, and they're genuinely worth the trip alone — particularly the Nishinomaru Garden, a paid inner garden known for cherry blossoms in spring and a clean, framed view of the tower itself.
Getting there
Osakajokoen Station and Tanimachi 4-chome Station both put you within easy walking distance of the park, and the castle tower is covered under the Osaka Amazing Pass if you're using one that day.
The walk from the nearest station gates to the tower itself is longer than it looks on a map — budget 15-20 extra minutes across the park grounds, especially in summer heat.