Oxford

Oxford needs a full day: the Bodleian Library (one of Europe's oldest) and the Radcliffe Camera, its iconic circular reading room, on the same walk through the university quarter. April-September, coinciding with the summer break, when some colleges open their courtyards to the public. It's expensive, with lodging prices similar to London's. It's the oldest English-speaking university in the world (founded before 1096) and has produced 28 British prime ministers, more than any other institution on the planet.