The funniest bit about this is how I discovered he did this, one day I got up too early thinking I was late, rushed out and drove off without my usual morning routine and when I heard a voice behind me asking if he could please get out of the car, my heart nearly stopped :)
This was around 1989, the location is Veemarkt in Amsterdam ('Veemarkt' is dutch for cattle market).
Back then homeless people in Amsterdam were fairly rare, now there are 100's of them.
One funny angle is that I was living there illegally myself, I didn't have a kitchen or a place to shower there and it being so quiet is why I got away with that. The people from other companies in that building knew that I was staying there overnight, but they in turn also didn't mind because they saw me as their 'free nightwatch', so there is some recurring element in there.
Anyway, it's ages ago, and if it happened today I'm not sure how I would respond, and I always wondered what happened to him but I did not see him after I moved (I went all the way to Poland).
https://www.google.com/maps/@52.3679788,4.9392218,3a,75y,187...
My unit was the one one from the corner on top (the entrance was at the back), about 60 square meters, an early version of a hackerspace I guess, and the bike path on the left wasn't there at the time, that's where there was parking space.
Now there are a few thousand people living on the other side of the street so you would never get away with it today anyway, someone would spot you there before the first day was out.
On the plus side: plenty of ventilation ;)