I live just a few blocks from the UW-Madison campus (40, 000 + students). It's a very old neighborhood with lots of old trees. There's a huge Blue Spruce in our terrace. One summer afternoon I was watering my window boxes when something flew onto a lower branch of the spruce (10 ft up). I guess it surprised me because it was a silent flier, not like the crows in our neighborhood. Turns out it was the an absolutely adorable Saw-Whet Owl. It sat there for several minutes--long enough to get my husband and daughters out to see him. A beautiful memory.
We also hear Great Horned owls, especially on very cold, still nights. I haven't been brave enough to bundle up and look for them.