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 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. I’ll pass it over to you. 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.