I lived in the lower unit of a duplex that was a converted 1880s house and saw mice in the basement and heard neighbors' complaints of mice upstairs, but we nev

I lived in the lower unit of a duplex that was a converted 1880s house and saw mice in the basement and heard neighbors' complaints of mice upstairs, but we never had them on the first floor. Later we moved to the upper unit and found that when the kitchen was put in to convert the house to a duplex, someone had cut a big hole for the kitchen pipes that left a clear view down to the basement-- and a perfect tunnel for mice. We covered the hole and didn't have any more mice after that.