Garrett Goss
Google
Great apartment-style rooms in a old brownstone, at a fraction of the cost of nearby hotels, in a great area.
The building itself is charming, and rooms are clean and comfortable. It's definitely quiet: I didn't see another visitor the whole time I stayed, despite the fact that all rooms were booked.
The surrounding area is beautiful and safe, with abundant greenery and plenty of small shops, cafes, and restaurants, and it's a short stroll from the river and the MIT campus, if that's why you're there.
There's no free breakfast, but rooms have a small kitchen (stove, microwave, sink, minifridge, tea kettle, coffee pot, assorted cookware and dishes utensils, etc.), bathroom, and other expected amenities, including cable tv and free wifi.
Highly recommended. It's the first place in Boston I'll recommend from now on.