Greater Boston used to have a scale model of the Solar System that was sponsored by the Museum of Science. (The Museum no longer sponsors the project and some of the planets, including Mercury in the museum lobby, are now gone.) The dome of the museum's planetarium is the sun; the most distant current planet, Neptune, was at the Square One Mall in Saugus, and Pluto was at the Riverside MBTA station.

More info about where the planets are and used to be: https://foursquare.com/eric_odea/list/museum-of-science-boston-community-solar-system