If you're a keen reader of detective fiction and have an hour to spare, may I suggest you watch the very comprehensive, entertaining lecture Dons, Deaths and Detectives: Oxford in Crime Fiction by Professor Colin Bundy.
For those in the market for a quick summary of the talk, the professor gives an outline of the Oxford crime canon, beginning with what are seen as the founding books: An Oxford Tragedy (1933) by J.C. Masterman, still regarded by some critics as perhaps the best of the bunch, Gaudy Night (1935) by Dorothy L. Sayers (Lord Peter Wimsey), and Death at the President's Lodging (1936) by Michael Innes (Inspector Appleby), all Golden Age novels using a college as the equivalent of the country house or hermetically sealed setting, all written by Oxford insiders.
The donnish detective 'type' (that winning combination of the erudite and the analytical) continues post-war but diversifies somewhat in pursuits, preoccupations and locations, see for example Professor Gervase Fen in The Case of the Gilded Fly and The Moving Toyshop by Edmund Crispin, the Ambrose Usher books of Jocelyn Davey (the character said to be based on Sir Isaiah Berlin), and the Hilary Tamar novels of Sarah Caudwell - "elegant, witty, subtle and complicated" - here's a very good article about Sarah Caudwell by fellow crime writer Martin Edwards; he mentions, inter alia, her book The Sirens Sang of Murder, "a saga of sex, international tax planning, and witchcraft", a must-read for the Cornflower Book Group, surely ...
The sub-genre goes on with the Kate Ivory mysteries by Veronica Stallwood, Jumping the Cracks and others featuring private investigator Sam Falconer by Victoria Blake, the parody Landscape with Dead Dons by Robert Robinson, and as an example of historical Oxford crime fiction the "very fine" An Instance Of The Fingerpost by Iain Pears.
Writers such as Antonia Fraser, Hazel Holt and Val McDermid have all brought their main characters to Oxford at least once, but in terms of series the best known is, of course, Colin Dexter's Inspector Morse. Although we have all the Morse novels I have never read them, preferring to keep in my mind the television versions and John Thaw's portrayal of an intensely romantic figure rather than the more misogynistic man of the books. The donnish detective character then continues in the Morse spin-off Lewis with Detective Sergeant Hathaway following on in the spirit of Innes's Inspector Appleby.
What makes Oxford such a popular setting for crime fiction? It's a place of inward-looking buildings and institutions, protected and picturesque, and having their own customs and rituals; its proximity to London is helpful in terms of plot, it's a seat of power with a population that is increasingly multi-cultural and highly intelligent; it's seen as a 'gilded' place, mystical, nostalgic, mysterious and very appealing, and when a crime is solved and order is restored, that act of restoration is itself a source of reassurance in a troubled world.
For that and more talks in the Oxford crime series click here.