Today is Oxford Open Doors, a fantastic initiative to allow access to all sorts of interesting places which ordinary folk don't usually get to see.
This is the ceiling of the Sheldonian, the university's official ceremonial hall, which was the first major design by Sir Christopher Wren.
To be honest, I found the actual building rather lifeless and even a bit shabby - but looking up was quite special.
Apparently the roof itself was a masterpiece of architectural design, made up of timber trusses and complicated cross beams supported by braces and screws - without any columns.
The oil painting is by King Charles II’s court painter, Robert Streater, with a 2004 project restoring the original colour scheme, last seen in the 1720s.
It shows Truth descending upon the Arts and Sciences and expelling ignorance from the University - a nice idea!