A tower is a tall building. Many castles have towers. Today, towers are very tall and some are used to send radio signals to people far away.
The Eiffel Tower is a landmark of Paris.
Cathedrals often have towers, this one is in Cadiz
A church with a well-visible tower.
A pagoda in Guangzhou
Skyscrapers are often called towers. This one is in Vienna
A tower used for radio and video transmissions
The tower on a mosque is called a minaret. This one is in Iran