Taking photos at night is mostly about getting focus, here I was setup on a tripod and set my focus on one of the windows, there was enough contrast for the auto focus to pick it up, I set my aperture to f7.1 to get a bit faster shutter speed.
Image: 5D Mk III, 24-105 f4 L IS
Again I got enough light on the window for auto focus to work and tried to maintain about 20 sec exposure to keep the stars pinpoint instead of streaks.
so some basic rules are keep the exposure as fast as you can at ISO 100, use a tripod, find contrast for your auto focus to work or switch to manual focus, if there are no stars or you want to impart movement somehow go with a longer exposure, if its very dark you may need to bump up your ISO to 1600 to get a faster shutter speed.
Its amazing what can be done with today's cameras, tomorrows, well ?.................