The Royal Fort Gatehouse, Bristol University. This is where some Prince surrendered Bristol in the civil war in 1645. This gatehouse is all that remains -the castle-like building behind is actually early C20, and where the physicists hang out.
But what does the sign from the other direction say? It says "Mathematics Accessible Entrance"
We are still trying to parse the sign.
1. This archway is more accessible to getting bits of maths in and out the university, on account of its parallel sides and arch on top, it is a mathematically correct entrance.
2. The university is doing some work on "Accessible Mathematics", as opposed to the complicated stuff like imaginary numbers and partial differential equations.