Cambridge

Cambridge needs 1 day: touring Harvard Yard, the original courtyard of the oldest university in the United States, founded in 1636, and crossing the Charles River to the MIT campus to see the Great Dome and its public sculptures, the same afternoon. April-October brings the most pleasant weather, with campuses full of students. It's expensive, due to housing demand tied to both universities. Separated from Boston only by the Charles River, it packs two of the world's most prestigious universities within less than 2 km of each other, something with no equivalent in any other city of its size.