The length of that ticking radiator in Copenhagen was one horizontal leg.
Well, my leg, stretched out horizontally.

To remember a place I try to find body parts that correspond with parts of the space. We often have some things in common, the space and I.
Sometimes I’m lazy and just do it from a distance. Like now. Sitting in this chair, finding that the top of the window frame is exactly the length of my lower arm if I twist my upper body to the right, lift the arm up with a 90 degree angle in the elbow and hold it up horizontally, blocking the window frame from my gaze.

That was a bit of a monologue. I tend to talk a lot when I’m nervous. Now it’s your turn. What do you have in common with the space surrounding you?
Take your time, find a couple of corresponding parts.
If you memorize these movements you can bring the space with you somewhere else.