A belfry is a tower or room in a tower, usually part of a church, where bells are hung and rung. If you've ever seen a tall church steeple with openings near the top, you're probably looking at a belfry. The bells inside might ring to call people to services, mark the hours of the day, or celebrate special occasions like weddings.

Belfries were especially important before people had clocks and phones. The bells served as a town's alarm system and timekeeper. They might ring to warn of danger, announce important news, or help people know when to gather. Some famous belfries, like the one in Bruges, Belgium, became symbols of their cities.

The word appears in the old phrase “bats in the belfry,” meaning someone is acting crazy or confused. Since belfries are high, dark, echoing spaces where bats sometimes roost, people imagined that having bats flying around in your head would make your thoughts scattered and strange. If someone has “bats in the belfry,” they're thinking or acting in an odd, mixed-up way.