A tortuous subway and street trolley good for spotting cute girls who don't want to talk, the MBTA Green Line provides an excellent excuse for being late to work in the morning. Of the original five street-level routes, only four remain as the A Line closed in the late 1970's. In a humerous insult to Boston University, the Boston College (B) line slices through the middle of campus; Boston College students are better served by the Riverside (D) line, so they do not ride the Boston College trolley.