The only place in North America that's fit for human habitation.
Okay, the only place I've been to in North America that's fit for human habitation. That narrows it down considerably...
In the summer, Cambridge is unbearably hot: Temperatures over 90 degrees are not rare. As soon as the weather becomes tolerable in September, the students return and take all the parking spaces. I live within easy walking distance of two good bookstores and several good record stores, and I once sighted Noam Chomsky at the supermarket. There are parks and people riding bicycles (like, see Charles River Reservation, I guess).
Most of the streets in Cambridge wind like cow paths: This is because at one time they were cow paths. It's like a maze. Those streets which are labelled (many aren't) will often have two names on the sign: A modern name, and the original name with a date. Some of the names are funny: Garden Street, for example, is subtitled "Great Swamp Way, 1634".
Parking in Cambridge can be hell; when the college kids are in town for the winter, I've spent half an hour trying to find a space in the evening. That part sucks.
Many of the buildings in Cambridge are old, and much of the city is built of brick. Many sidewalks are of brick, too, and they're very slippery in the winter -- but so what? It looks wonderful.