The tall stacks of the Boston Edison (now Exelon Energy) Mystic Power Station on the Mystic River in Everett mark the most prominent building of the extensive industrial corridor along the Everett riverfront. The space stretches along the Mystic marshes from gas and fuel repositories at Island End River to the south to the General Electric Company factories along the Malden River to the north. The brick and reinforced concrete Boston Edison complex was designed to provide power for towns on the northern side of Boston. The power was produced by self-contained units, which included one boiler and one turbo generator. This process allowed for generators to be shut down or turned on depending on the demand for electricity. The building was continually expanded, and additional boiler/generator units were added (in 1945, 1947, 1957, 1959, and 1961). In 1975, Mystic 7 was put into service replacing the units built in the 1940s.