As you walk the streets of Oxford, know that you are inhaling air breathed by geniuses of every ilk. Oxford University, the oldest English-speaking university in the world (a center of learning since at least 1096), is an education powerhouse without rival. Christopher Wren, William Penn, Lewis Carroll, Oscar Wilde, J. R. R. Tolkien, T. E. Lawrence, Indira Gandhi, Margaret Thatcher, Steven Hawking, Tony Blair, Hugh Grant, and King Abdullah all hit the books here. Unlike American universities, where buildings sprawl across acres and students from many disciplines share high-rise housing, Oxford is separated into 39 compact colleges, each with its own buildings, lodgings, traditions, and hours open to visitors. The picture-perfect choice for visitors is Christ Church College, familiar to Ame ...