A tower is a tall, thin building. In Medieval times, castle towers served the purpose of a lookout tower across the surrounding terrain, or else a prison. Churches were also built with towers or steeples to contain bells.
- The Twin Towers of the former World Trade Centre, New York
- The Tower of London
- The Tower of Babel
- The Leaning Tower of Pisa
- The Two Towers by J.R.R. Tolkien (Book)