The Imperial Palace, home of the imperial family, is the heart and soul of Tokyo. Built on the very spot where the massive Edo Castle compound used to stand during the days of the Tokugawa shogunate, it became the imperial home upon its completion in 1888 and is the residence of Emperor Akihito, 125th emperor of Japan (who will abdicate in 2019 and be followed by his son, Crown Prince Naruhito). Destroyed during air raids in 1945, the palace was rebuilt in 1968 using the principles of traditional Japanese architecture. But don’t expect to get a good look at it; most of the palace grounds’ 114 hectares (282 acres) are off-limits to the public, with the exception of 2 days a year when the royal family makes an appearance before the throngs: January 2 and on the emperor’s birthday (Dec 23 in 2018; undecided for 2019 and 2020).
You can visit Imperial Palace grounds (not any buildings) on free guided tours conducted in Japanese and English Tuesday through Saturday at 10am and 1:30pm (1:30pm tour not available July 21–Aug 31), but reservations are mandatory and are accepted up to 1 month in advance. Easiest is to book online, which you must do at least 4 days in advance at the website below. Alternatively, you can make a same-day or advance reservation by calling the number below, but note that only 50 tour participants are accepted. Tours last about 75 minutes and include official buildings, the inner moat, historic fortifications, and Nijubashi Bridge. I recommend this tour only if you have seen Tokyo’s other top attractions (and it doesn’t come close to the more impressive imperial palace tours in Kyoto).
Otherwise, you'll have to console yourself with a camera shot of the palace from the southeast side of Nijubashi Bridge, where the moat and the palace turrets show above the trees. Most Japanese tourists make brief stops here to pay their respects. The wide moat, lined with cherry trees, is especially beautiful in the spring. You might even want to spend an hour strolling the 4.8km (3 miles) around the palace and moat. But the most important thing to do in the palace's vicinity is visit its Higashi Gyoen (East Garden), where you'll find what's left of the central keep of old Edo Castle, the stone foundation.