Osaka Castle (or Osaka-jō) has a long, interesting history, and what remains of it is a feudal reminder sitting proudly in the middle of a modern Japanese city.
The charming park surrounding the main tower is a nice break from the stresses of urban travel, with plenty of long, winding roads perfect for a morning jog or evening stroll. Near the gate of the main tower are several places to grab a bite to eat and a training hall where you can stick your head in and see high school students practicing Japanese martial arts.
Once inside castle grounds, there are several souvenir shops to pick up gifts, postcards and other knickknacks. The castle has many temporary exhibits throughout the year along with its permanent collection. The entrance is equipped with an elevator and is handicap-accessible.
On your way out, be sure to stop by the Morinomiya station entrance. At night, musicians practice their licks under the eves of the bicycle parking area. Try Kame Ramen next to Morinomiya station for a fine bowl of ramen for around $7.00. Use either the Osaka-jo Koen or Morinomiya stations to get to the castle park.