Osaka Castle and gardens is easily accessible by train and subway. The grounds are located a ten minute walk from either Osaka-jyo Koen train station or Tanimachi 4-chome subway station. If you can't find signs or a group of people to follow, the station employees are always happy to help lost travellers. The castle and grounds open at 9 a.m. and especially in festival season, is busy all day.

Osaka Castle's Main Tower
Construction of Osaka Castle first began in 1583 by
Toyotomi Hideyoshi. It was destroyed and rebuilt time and time again, during the shogunate period, the
Meiji Restoration and World War Two. Then there is one time in 1665, where it was burnt down as lightning struck gunpowder supplies. The final restoration, after World War Two, was completed in 1997. During this restoration the inside of the castle was turned into a museum which is open to the public and contains artwork, artifacts and offers a view from the top level of surround Osaka.
It is easy to spend up to two or three hours wandering around the castle gardens and exploring its fortifications. There is however, no need for much preparation as located all through the grounds are restaurants, cafes, vending machine and areas to rest or picnic. During festival time or sakura season however, be prepared for the
Battle of Sekigahara 2 as groups and families hunt for the best sitting spots.

Osaka Castle and gardens, contrasting the modern city background. JKT-c./Wikimedia Commons
Hang around the main tower long enough and you're sure to see some buskers in action. Ranging from juggling and circus style acts to more traditional Japanese pursuits such as Taiko drumming, it's worth grabbing a cone of sakura flavoured ice cream and settling in to appreciate the scene.
Also located in the gardens is
Houkoku shrine (shinto), where there are often Japanese style wedding processions.
Osaka Castle and Gardens are free to walk around, entering the central tower however will cost 600 yen (at time of writing). Food around the castle ranges from 500 to 800 yen for a meal.