structure with height greater than width
A tower is a tall structure. Towers are different from buildings because people do not live in them. Many castles have towers. Today, towers are very tall. Some things they are used for are to send radio signals, for observation, or to hold up bridges.
The Eiffel Tower is a landmark of Paris.
Cathedrals often have towers, this one is in Cadiz
A church with a well-visible tower.
Skyscrapers are often called towers. This one is in Vienna