Which university did J.R.R. Tolkien attend as an undergraduate, studying classics before English?

J.R.R. Tolkien attended the University of Oxford as an undergraduate.

He studied at Exeter College, Oxford, beginning in 1911. Tolkien initially focused on Classics, but he later changed to the English Language and Literature course. His studies developed the linguistic and medieval interests that became central to both his academic work and his invented languages.

Tolkien’s Oxford career continued long after his undergraduate years. He became Rawlinson and Bosworth Professor of Anglo-Saxon in 1925 and Merton Professor of English Language and Literature in 1945. Oxford also provided the setting for his friendships with writers including C.S. Lewis, with whom he was associated with the informal literary group known as the Inklings.

Some summaries mention Exeter College rather than the university, but Exeter was the specific Oxford college Tolkien attended. The university and college are therefore related answers at different levels; the university-level answer is the University of Oxford.