East Cambridge is filled with old wooden tenement houses that were built for factory workers back about a hundred years ago. They are densely packed. Get one burning, add a little wind, and you can get a conflagration. The last big one in the area was the Chelsea fire of 1973. That one took out 16 acres of urban structures.
Yep. About 15 or 20 feet between them, enough for a driveway. Sometimes less.