4. University of Oxford

At number four is University of Oxford, UK.

One of the oldest colleges in Britain, it is believed that the history of teaching at Oxford dates back to the 11th century.

It currently enrolls about 20,000 students annually across various programmes at undergraduate and post graduate levels.

Among its notable alumni include leaders like former British prime ministers like Clement Atlee, Margaret Thatcher, Tony Blair, and current and former Indian prime ministers Manmohan Singh and Indira Gandhi respectively.

Writers like Lewis Carol, Oscar Wilde, Prof. JRR Tolkein, scientist Stephen Hawking, actor Hugh Grant also sudied at Oxford.