King's Arms, Oxford

You'll find this proper boozer squeezed onto Holywell Street, where the cobbles practically whisper with centuries of scholarly debate. The King's Arms has been pouring pints since the 17th century, and it shows – low ceilings, dark wood, and that particular patina that only comes from generations of academics gesticulating wildly over their bitter. The crowd is brilliantly mixed: don lecturers nursing their third pint while marking essays, undergrads celebrating surviving prelims, and the occasional tourist who's wandered off the beaten track. The Young's ales are well-kept, the atmosphere thick with conversation, and the location absolutely perfect if you're exploring the old quarter around New College Lane. It's the sort of place where you pop in for one and emerge three hours later, slightly worse for wear but significantly better informed about medieval history or particle physics.