 Over time, deferred maintenance on the Sullivan Square station took its toll, and when the Charlestown Elevated came down in the 1970s, the once-magnificent transportation hub was considered by some to be beyond saving.The current Sullivan Square station was opened as part of the Haymarket North Extension project on April 7, 1975, on top of now-defunct Boston and Maine Railroad right-of-way.Shortly thereafter, a mysterious fire broke out in the old station, which was subsequently razed and repurposed as an MBTA service vehicle parking lot.