Bell-towers were first built to contain a bell to summon people to worship in the church or to ring the curfew or a danger signal. They were constructed in such a way that the sound of the bell ringing could be heard as far away as possible.

In the past, church bells used to mark all the main stages of the day such as dawn, dusk and the passage of the hours. Farmers working in the fields would regulate their lives to the sound of the church bells.

Bell-towers are usually tall structures. They can be found, square or many-sided, Gothic bell-towers, also known as steeples, have a long, sharply tapering top called a spire. The great spire of Salisbury Cathedral, built in 1250, is about 125 meters high.

In Italy, most bell-towers are square and are known as campaniles. The earliest are dated between the seventh and tenth centuries and are plain, round towers with a few small, round-arched openings grouped near the top. Round campaniles occasionally occurred in later periods, as in the famous leaning tower of Pisa (begun in 1174) which is a more elaborate version of this type.