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.
How to trace out a trefoil knot in the Fry Building
> Start at the west staircase on G and go up to 2.
> Go through the common room to the east lift and down to LG.
> Pass the vending machine, go up the small set of steps to the reception area and up the spiral staircase to 1.
> Go to the north staircase and down to G.
> Exit the building by the accessible door, walk down University Road and pass under the bridge to the other geography building. Reenter the building through the revolving doors.
> Go to the south staircase and up to G.
> Go to the east staircase and up to 1.
> Go to lecture theatre G.10 and exit on G.
> Staying on the right, you can walk back to the west staircase.
Full working and a few diagrams can be found in my handwritten notes.