The Sheldonian Theatre was designed by Christopher Wren(1632-1723) as one of his first buildings in 1664-68, even before building St Paul's Cathedral.  It is used today as the place for the graduation ceremony for all Oxford graduations, however they have them in a series of almost continuous ceremonies in the last weeks of the year according to my sources.  It is also a place of concerts and can be rented for special occasions.