this is harvard yard; the oldest part and center of the campus of harvard university. the oldest building still standing dates back from 1720. harvard yard was locked down for several weeks last year, when some students played "occupy boston" and had tents in the grassy area behind the people you see in the pic (as you can see in my old post here). it was then only accessible to those with a harvard id, and thus rather empty, while normally its a very touristy area! it is also the home of harvard freshmen (first year students); 13 of the 17 freshman dormitories are located in harvard yard (you see 2 of them in the pic). must be weird living in a tourist hotspot, although i think most harvard students actually enjoy this attention....
as you can see, also here the grass turned freshly green; it really makes everything around here very pretty (only now you are not allowed to walk on it anymore).