Towers have been built by mankind since prehistoric times. The walls of ancient Jericho, one of the first city walls ever built, was complemented by a stone tower. Later civilizations often built watchtowers as part of their fortifications to provide a high, safe place from which a guard could observe the surrounding area.

In the last two millenniums all sorts of towers have been built including bell towers, clock towers, minarets and communication towers. An overview of the most famous towers in the world:

1. Eiffel Tower

The Eiffel Tower is a symbol of Paris and France and one of the most famous landmarks in the world. The tower was built by Gustave Eiffel as the entrance arch for the International Exhibition of Paris of 1889. With a height of 300 meters (984 feet) it was the tallest tower in the world until 1930, when the Chrysler Building in New York was completed. Since it’s construction more than 200,000,000 people have visited the Eiffel Tower making it the most visited paid monument in the world.

2. Leaning Tower of Pisa

The world famous Pisa Tower was built over a period of about 177 years. Soon after the construction started in 1173 the tower began to sink due to a poorly laid foundation and was left alone for almost a century. When the construction resumed the engineers built higher floors with one side taller than the other to compensate for the tilt and the tower was finally finished in the 2nd half of the 14th century. Since 2001, the famous tower in Pisa is again open to those wishing to climb it’s 296 steps.

3. Big Ben

Celebrating its 150th birthday this year, the Big Ben Clock Tower is one of the most famous tourist attractions in London. The name Big Ben actually refers not to the clock tower itself, but to the 13 ton bell housed within the tower and takes its name from the man who first ordered the bell, Sir Benjamin Hall. It is the 3th largest free-standing clock tower in the world.

4. CN Tower

Located in the heart of Downtown Toronto, the CN Tower is Canada’s most recognizable icon. The communication tower was built from 1973 to 1976 by the railway company “Canadian National” and standing 553.33 meters (1,815.4 ft) tall was the tallest structure in the world for over 30 years until it was surpassed in height by the Burj Dubai.

5. Belem Tower

Belém Tower was built in the early 16th century as part of a defense system to protect the city of Lisbon. It was the starting point for many navigators who set out to discover new trade routes and has become a monument to Portugal’s Age of Discovery.

6. The Two Towers of Bologna

Not to be confused with the Lord of the Rings movie, The two famous towers of Bologna in Italy are named after the families who are credited for their construction between 1109 and 1119. The Asinelli Tower, with a height of 97.2 meter, is the tallest tower in Bologna. The Garisenda Tower was initially 60 meter long but was lowered in the 14th century to 48 meter in order to make it safer.