Matt Parker, in this video, investigates whether the London underground is knotted (see that video for what this means). Indeed he and his companions managed to tie a trefoil knot by taking journeys on the tube. Therefore, when me and my colleagues in Bristol moved into the Fry Building, we naturally asked whether we could tie a trefoil knot by walking around our new mathematics building.

If you allow us to enter the and exit the building exactly once, then we discovered the following way to tie a trefoil knot in the Fry Building.

Full working and a few diagrams can be found in my handwritten notes.