A tower is a tall, narrow structure that rises high above its surroundings. Towers can stand alone, like a lighthouse warning ships away from dangerous rocks, or form part of a larger building, like the bell tower of a church or the pointed towers of a medieval castle.

People build towers for many reasons. Some towers help us see farther: forest rangers once climbed fire towers to spot distant smoke. Some towers broadcast signals: radio towers and cell phone towers send invisible waves across miles of landscape. Some towers store things: water towers hold a town's water supply high up so gravity can push it through pipes to homes below.

The word also describes things that resemble towers in shape. You might stack blocks into a tower that reaches toward the ceiling, or see a towering pile of pancakes at breakfast. When something towers over you, it rises so high above that it makes you feel small, like when you stand at the base of a redwood tree and look up at its towering trunk.

Famous towers include the Eiffel Tower in Paris, the Leaning Tower of Pisa in Italy, and the clock tower called Elizabeth Tower in London. Each became a symbol of its city partly because towers are hard to miss: they reach for the sky in a way that makes people stop and look up.