One of my favorite Sunday things about Tokyo is street closures. During daytime hours they close off some of the main thoroughfares in busy areas to vehicular traffic and pedestrians can roam freely. Happens in Akihabara, Ginza, Shinjuku, I'm sure other areas as well. Also around the Imperial Palace, where you can borrow a bicycle and ride around, weather permitting. http://www.jbpi.or.jp/english/pc1.html