We ended up eating oysters in Jericho on Valentine's Day this year (lesson learned - tempura oysters are amazing) and on the way home noted that there seemed to be a lot less building work going on around the old observatory, and decided to see if the old cut-through route to Woodstock Road was open again.
Not only was it open again (well, we got stopped by barriers twice, but that was just betting on the wrong route) but we also ended up here:
This is the front garden of the Oxford Mathematical Institute's Andrew Wiles Building. It was a little dark for most of the planting, but the hellebores did look very pretty in the garden lights; and the metal curves on the Penrose tiles were fairly gleaming. We sat on the garden borders briefly, contemplating the tiles and the glass beyond. It is a beautiful garden; very rational, very tidy, very satisfying.
I would highly recommend coming upon this garden unexpectedly, at night, and with no idea what you will find around the next corner. The thrill of discovery tempers the discipline of line; and glories loom out of the darkness, glistening.
But, you can of course see it much better and more clearly by day; and on the Mathematics Institute website you can see more of the building by drone flight, and an epic timelapse of the laying of the Penrose Tiles.