The top of many tall buildings have bars or restaurants where you can take photos. No one ever really seems to mind. One BIG problem though is the lights inside the bar. They bounce off the windows and create an awful reflection. I usually contact someone that works there and give them a tip to turn off all the lights for 5 minutes while I take the photo. I am sure to set everything up first, so I can get to snapping... especially since as soon as the lights go off, a mild amount of panic ensues from the patrons.