So it is in Odaiba but where is it exactly located? I wasn’t there in 2009 when it was first up on display but judging from pics around the web taken years ago, I would say it’s at a different location. Maybe somewhere near the original spot I don’t know. But anyway as of right now, it is located as you can see from the first 2 photos, Diver City Plaza. The building looks to be a mall but is still under construction. The nearest train station is the Fune-no-kagakukan station (船の科学館駅) on the Yurikamome line. The easier way to get on the train is to transfer at JR Shimbashi station.
Full article: http://gordonator.com/2012/01/13/odaiba-gundam-rx-78/