"History, academia and some more besides. " a Oxford Travel Page by planxty

Oxford's very early history is shrouded in mystery, and it seems that nothing of great note happened there until Saxon times, when Alfred the Great took a hand. It was a time when successive invasions from the European mainland were sweeping Britain and Alfred (himself a Saxon from an earlier invasion) possibly founded the town to repel the newer Danish invaders. King Canute (of the trying to hold back the sea fame) was crowned here in 1018.

The next news in English history was the Norman invasion, and Oxford had it's first Norman castle in 1071. It is probable that the academic tradition, which persists to this day, started around then. From then, the toen continued to grow steadily.

Oxford rose to prominence during the English Civil War of the 17th century when the Town v. Gown issue (i.e. the locals versus the academics of the Colleges) was raised. The locals were Parliamentarian whilst the Colleges were Royalist.

Subsequent to the Civil War, the town continued to grow, like many others in England, and is now firmly on the tourist trail for visitors to Britain alongside London, York, Stratford, Edinburgh etc. etc.

Decent travel options from London make it a viable day trip even if you haven't got time to spend a night there. It's certainly well worth a visit.