These lights used to be fairly common throughout Boston's business districts. The poles were rebar-reinforced concrete and were designed to last virtually forever. The fixture shown is a GE Form 109 mercury luminaire. These were produced from 1949 through 1954 and accomodated 250 or 400-watt mercury vapor lamps. They were made before their ballasts (transformers) were integral inside the fixture; the unit that powered this luminaire is seen mounted on the pole. Owing to their age and more efficient light sources that have been utilized for outdoor lighting, these fixtures are very rare today.