When I was in my early twenties I lived in a city and had a third-floor apartment in a three-story building. My bedroom window faced the building next door, separated only by a narrow catwalk. On the second floor across and one window over was the bedroom of a young single girl with dark hair, cute and slender and in her early to mid twenties. I only saw her a couple of times over there, but she was close enough that I could hear her and her roommate talking sometimes. Neither building had air conditioning so on summer nights shades and windows were open by necessity.
Late one Sunday evening after dark I saw her over there, and kept my lights out as it appeared that she might be getting ready for bed. It's been so long that I don't recall details of how I hid, but I would have stayed discreet and quiet and still in my dark room, as there were other windows very close where someone could have spotted me, or even heard me.