The Rainbow Bridge connects Tokyo's mainland to the reclaimed Odaiba island waterfront. You use the Yurikamome train line, drive on it with your car, or the best option would be to walk it. You can see some amazing views from the bridge, both looking towards Tokyo as well as towards Odaiba. The walk is about 10 minutes long, if you don't stop to take many photos, and much longer if you spend the time to enjoy the views. Keep in mind the bridge will close half an hour before 9 p.m. in the summer and before 6 p.m. in winter.
Find out more about Rainbow Bridge.