The Imperial Palace, residence of the current Emperor of Japan, is situated on the site of Edo Castle. Most of the Imperial Palace and grounds are not open to the public, but kids can explore the East Garden, and climb up stone foundations of the great five-story tower (Tenshudai donjon) of Edo Castle.
Today it's hard to grasp just how big Edo Castle was - it covered an area of about 10 miles (16 kilometers). When you walk over to the Imperial Palace from Tokyo Station, that's approximately the distance from the outer moat of the castle.
Imperial Palace East Garden walking tour - Here's our favorite walking tour for kids through the East Garden. Entrance is free, the East Garden is closed on Mondays and Fridays, and year-end holidays (last weekend in December).
From Otemachi subway station (exit C13), start out on Uchibori street. Walk over the moat and through the Ote-mon Gate (originally there were 99 gates to the castle). This is a good example of Japanese castle architecture, with the first gate leading into a courtyard, which would trap invaders, and then a second, even more fortified gate.
Walk straight, past the Doshin-bansho guardhouse, then turn right in the direction of the Ninomaru garden. As you walk along, on the left is a portion of the moat, and a thick wall of huge granite stones,(transported here in the early 1600s from many miles away).
Take the path into the Ninomaru garden, and wander through this lovely traditional landscaped garden, with a large pond, stone lantern, wooden bridge, paths, pine trees, willows, azaleas, irises, and cherry trees.
After you've explored the garden, retrace your steps, going back to the guardhouse, turn to go right up the hill to the Honmaru, central castle keep area. The Honmaru included official buildings of the shogun (audience halls etc.), shogun's residence, and a separate complex for hundreds of court ladies and their attendants.
When you get to the top of the slope, there's a wide grassy area, once site of the Honmaru. Feel free to bring a picnic and flop down on the grass, just like local families.
To the right of the grassy area is a rest house and snack bar, take the short path to a lookout ("observatory"). From the top of the granite wall, kids can look down to the moat below (which you saw at the bottom when walking on the way to the Ninomaru garden).
At the north end of the grassy area is the Tenshudai donjon, the remaining stone walls of the castle keep. Go up the walkway, and at the top, kids can imagine they are surrounded by a gleaming black tower, five-stories high, covered in golden roof tiles. It was the tallest castle keep in Japan.
From the donjon, take the path north, then go right for the exit at the Hirakawa-mon Gate. Walk across the bridge, and take a look back at the moats and defensive walls of the castle. Walk to the Takebashi subway stop, which is close by, or if you want to walk further, walk east around on Uchibori-dori, until you're at the Ote-mon Gate, where you started.
Imperial Palace Outer Garden -Looking for a place to kids to stretch their legs, the Imperial Palace Outer Garden has plenty of open space. It's a public park, with lots of benches for a picnic lunch. For samurai fans, in the southeast corner of the park is the super bronze statue of samurai Kusunoki Masashige on horseback. (For the statue, the most convenient subway is Hibiya).
Go boating - On the west side of Kitanomaru Park (just north of the Imperial Palace East Garden), at Chidorigafuchi Boat Arena rent pedal boats or row boats, and pedal around the ancient moats. March to November, 11am - 5:30pm, closed on Mondays.
Yushu-kan (Yasukuni Shrine) - Just north of Kitanomaru Park is the Yasukuni Shrine, honoring Japanese soldiers who died fighting. Yushu-kan, the military museum, has samurai armor, swords, modern weapons and tanks, and Japanese World War II airplanes.