A belfry is a common word for Bell Towers in Flemish cities, either attached to a structure or freestanding. These towers were used by watchmen as a lookout to see enemy armies or fires on time.
Origin of the word Belfry
The words bell and belfry seem obviously related, but in fact the bel- portion of belfry had nothing to do with bells until comparatively recently. Belfry goes back to a compound formed in the prehistoric common ancestor of the Germanic languages. It is generally agreed that the second part of this compound is the element *frij-, meaning "peace, safety." The first element is either *bergan, "to protect," which would yield a compound meaning "a defensive place of shelter," or *berg-, "a high place," which would yield a compound meaning "a high place of safety, tower."