Even though we live in the city of Chicago we are adjacent to a forest preserve and have lots of critters -- even deer. Fortunately we've not had rats but we do have possums -- which look very much like rats. One got into the basement window well this summer and could not get out. When I turned the light on in the basement it lunged at the window which was a frightening sight! Teeth all bared and claws out. We put a board down in the well and it was able to climb out.

I've noticed it around again lately -- actually Edwina has noticed it and called it to my attention.

Perhaps you can tell yourself it is a possum rather than a rat?