Yukiko and I joined the walking tour inside the Imperial Palace (the former Edo Castle).
The Palace still occupies 115hr at the very center of Tokyo, and it surely is the main symbol of Tokyo.
Atmosphere there was so cool and silent that we might forget we are in the very center of Tokyo.
Although our cycling tour doesn’t include the visit inside the Palace, you can personally apply for the visit here.
Imperial Household Agency
http://sankan.kunaicho.go.jp/english/index.html
Tours are held on weekdays and English audio guide is also available.