Inspired by your website I had Nienke from Stadshout Amsterdam make this for my two cats Dexter and Louis. As you can see, it's quite high, about 9 meters or so. Louis went down twice, Dexter is still a bit afraid of hights. But for now, they think it's too cold to go outside. Hopefully they will use it more often when temperatures will go up again.
But thanks a lot for the inspiration!