It's a little more complicated than I've laid out here. There's not a hard boundary between the MIT campus and the rest of the city, in contrast with Harvard Yard on the other side of Cambridge, which is surrounded by high brick walls. Cambridge is an old city and MIT is, for a New England university, fairly young--not to mention that for the first few decades it was at a different location than today, in Boston proper. I'm pretty sure the road was there long before the first university building.