One of my hobbies as a stupid young man was breaking into roof spaces connected to my city's skywalk system, which I lived in.

You would be surprised how many buildings have these inside them, where you can't see them at all. If it's too difficult to get them rooftop or there's a code against them, or they don't want residents complaining about 5G in their buttholes, they just go inside the elevator room or somewhere tucked away.