A tower is a tall structure, taller than it is wide, often by a significant factor. Towers are distinguished from masts by their lack of guy-wires and are therefore, along with tall buildings, self-supporting structures. Towers are specifically distinguished from buildings in that they are built not to be habitable but to serve other functions using the

height Height is measure of vertical distance, either vertical extent (how "tall" something or someone is) or vertical position (how "high" a point is). For example, "The height of that building is 50 m" or "The height of an airplane in-flight is ab ...

of the tower. For example, the height of a clock tower improves the visibility of the clock, and the height of a tower in a fortified building such as a castle increases the visibility of the surroundings for defensive purposes. Towers may also be built for observation, leisure, or

telecommunication Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...

purposes. A tower can stand alone or be supported by adjacent buildings, or it may be a feature on top of a larger structure or building.

Etymology

Old English Old English (, ), or Anglo-Saxon, is the earliest recorded form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlers in the mid-5th c ...

''torr'' is from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''turris'' via

Old French Old French (, , ; Modern French: ) was the language spoken in most of the northern half of France from approximately the 8th to the 14th centuries. Rather than a unified language, Old French was a linkage of Romance dialects, mutually intellig ...

''tor''. The Latin term together with

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

τύρσις was loaned from a pre-Indo-European Mediterranean language, connected with the Illyrian toponym Βου-δοργίς. With the Lydian toponyms Τύρρα, Τύρσα, it has been connected with the ethnonym Τυρρήνιοι as well as with ''Tusci'' (from ''*Turs-ci''), the Greek and Latin names for the

Etruscans The Etruscan civilization () was developed by a people of Etruria in ancient Italy with a common language and culture who formed a federation of city-states. After conquering adjacent lands, its territory covered, at its greatest extent, rou ...

(Kretschmer Glotta 22, 110ff.)

History

Towers have been used by mankind since prehistoric times. The oldest known may be the circular stone tower in walls of Neolithic Jericho (8000 BC). Some of the earliest towers were ziggurats, which existed in Sumerian architecture since the 4th millennium BC. The most famous ziggurats include the Sumerian Ziggurat of Ur, built in the 3rd millennium BC, and the Etemenanki, one of the most famous examples of Babylonian architecture. Some of the earliest surviving examples are the broch structures in northern

Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...

, which are conical tower houses. These and other examples from

Phoenicia Phoenicia () was an ancient thalassocratic civilization originating in the Levant region of the eastern Mediterranean, primarily located in modern Lebanon. The territory of the Phoenician city-states extended and shrank throughout their histor ...

n and Roman cultures emphasised the use of a tower in fortification and sentinel roles. For example, the name of the Moroccan city of Mogador, founded in the first millennium BC, is derived from the Phoenician word for

watchtower A watchtower or watch tower is a type of fortification used in many parts of the world. It differs from a regular tower in that its primary use is military and from a turret in that it is usually a freestanding structure. Its main purpose is to ...

('migdol'). The Romans utilised octagonal towers as elements of

Diocletian's Palace Diocletian's Palace ( hr, Dioklecijanova palača, ) is an ancient palace built for the Roman emperor Diocletian at the turn of the fourth century AD, which today forms about half the old town of Split, Croatia. While it is referred to as a "pala ...

Croatia , image_flag = Flag of Croatia.svg , image_coat = Coat of arms of Croatia.svg , anthem = "Lijepa naša domovino"("Our Beautiful Homeland") , image_map = , map_caption = , capit ...

, which monument dates to approximately 300 AD, while the

Servian Walls The Servian Wall ( la, Murus Servii Tullii; it, Mura Serviane) was an ancient Roman defensive barrier constructed around the city of Rome in the early 4th century BC. The wall was built of volcanic tuff and was up to in height in places, wide ...

(4th century BC) and the Aurelian Walls (3rd century AD) featured square ones. The Chinese used towers as integrated elements of the

Great Wall of China The Great Wall of China (, literally "ten thousand ''li'' wall") is a series of fortifications that were built across the historical northern borders of ancient Chinese states and Imperial China as protection against various nomadic gro ...

in 210 BC during the

Qin Dynasty The Qin dynasty ( ; zh, c=秦朝, p=Qín cháo, w=), or Ch'in dynasty in Wade–Giles romanization ( zh, c=, p=, w=Ch'in ch'ao), was the first dynasty of Imperial China. Named for its heartland in Qin state (modern Gansu and Shaanxi), ...

. Towers were also an important element of

castles A castle is a type of fortified structure built during the Middle Ages predominantly by the nobility or royalty and by military orders. Scholars debate the scope of the word ''castle'', but usually consider it to be the private fortified ...

Other well known towers include the

Leaning Tower of Pisa The Leaning Tower of Pisa ( it, torre pendente di Pisa), or simply, the Tower of Pisa (''torre di Pisa'' ), is the ''campanile'', or freestanding bell tower, of Pisa Cathedral. It is known for its nearly four-degree lean, the result of an unst ...

in Pisa, Italy built from 1173 until 1372, the Two Towers in Bologna, Italy built from 1109 until 1119 and the Towers of Pavia (25 survive), built between 11th and 13th century. The Himalayan Towers are stone towers located chiefly in

Tibet Tibet (; ''Böd''; ) is a region in East Asia, covering much of the Tibetan Plateau and spanning about . It is the traditional homeland of the Tibetan people. Also resident on the plateau are some other ethnic groups such as Monpa, Taman ...

built approximately 14th to 15th century. Dana Thomas, "Towers to the Heavens"
''Newsweek'', 2003-11-15

Mechanics

Up to a certain height, a tower can be made with the supporting structure with parallel sides. However, above a certain height, the compressive load of the material is exceeded, and the tower will fail. This can be avoided if the tower's support structure tapers up the building. A second limit is that of buckling—the structure requires sufficient stiffness to avoid breaking under the loads it faces, especially those due to winds. Many very tall towers have their support structures at the periphery of the building, which greatly increases the overall stiffness. A third limit is dynamic; a tower is subject to varying winds, vortex shedding, seismic disturbances etc. These are often dealt with through a combination of simple strength and stiffness, as well as in some cases tuned mass dampers to damp out movements. Varying or tapering the outer aspect of the tower with height avoids vibrations due to vortex shedding occurring along the entire building simultaneously.

Functions

Although not correctly defined as towers, many modern high-rise buildings (in particular skyscraper) have 'tower' in their name or are colloquially called 'towers'. Skyscrapers are more properly classified as 'buildings'. In the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...

, tall domestic buildings are referred to as tower blocks. In the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

, the original World Trade Center had the nickname the Twin Towers, a name shared with the

Petronas Twin Towers The Petronas Towers, also known as the Petronas Twin Towers or KLCC Twin Towers, ( Malay: ''Menara Berkembar Petronas'') are 88-storey supertall skyscrapers in Kuala Lumpur, Malaysia, standing at . From 1998 to 2003, they were officially desig ...

Kuala Lumpur , anthem = ''Maju dan Sejahtera'' , image_map = , map_caption = , pushpin_map = Malaysia#Southeast Asia#Asia , pushpin_map_caption = , coordinates = , sub ...

. In addition some of the structures listed below do not follow the strict criteria used at List of tallest towers.

Strategic advantages

The tower throughout history has provided its users with an advantage in surveying defensive positions and obtaining a better view of the surrounding areas, including battlefields. They were constructed on

defensive walls A defensive wall is a fortification usually used to protect a city, town or other settlement from potential aggressors. The walls can range from simple palisades or earthworks to extensive military fortifications with towers, bastions and gates ...

, or rolled near a target (see

siege tower A Roman siege tower or breaching tower (or in the Middle Ages, a belfry''Castle: Stephen Biesty's Cross-Sections''. Dorling Kindersley Pub (T); 1st American edition (September 1994). Siege towers were invented in 300 BC. ) is a specialized siege ...

). Today, strategic-use towers are still used at prisons, military camps, and defensive perimeters.

Potential energy

By using gravity to move objects or substances downward, a tower can be used to store items or liquids like a

storage silo A silo (from the Greek σιρός – ''siros'', "pit for holding grain") is a structure for storing bulk materials. Silos are used in agriculture to store fermented feed known as silage, not to be confused with a grain bin, which is used ...

or a water tower, or aim an object into the earth such as a drilling tower. Ski-jump ramps use the same idea, and in the absence of a natural mountain slope or hill, can be human-made.

Communication enhancement

In history, simple towers like lighthouses, bell towers, clock towers, signal towers and minarets were used to communicate information over greater distances. In more recent years,

radio mast Radio masts and towers are typically tall structures designed to support antennas for telecommunications and broadcasting, including television. There are two main types: guyed and self-supporting structures. They are among the tallest human-made ...

s and cell phone towers facilitate communication by expanding the range of the transmitter. The

CN Tower The CN Tower (french: Tour CN) is a concrete communications and observation tower in downtown Toronto, Ontario, Canada. Built on the former Railway Lands, it was completed in 1976. Its name "CN" referred to Canadian National, the railway c ...

in Toronto, Ontario, Canada was built as a communications tower, with the capability to act as both a transmitter and repeater.

Transportation support

Towers can also be used to support bridges, and can reach heights that rival some of the tallest buildings above-water. Their use is most prevalent in suspension bridges and

cable-stayed bridge A cable-stayed bridge has one or more ''towers'' (or ''pylons''), from which cables support the bridge deck. A distinctive feature are the cables or stays, which run directly from the tower to the deck, normally forming a fan-like pattern ...

s. The use of the pylon, a simple tower structure, has also helped to build railroad bridges, mass-transit systems, and harbors. Control towers are used to give visibility to help direct aviation traffic.

Other

* To access tall or high objects:

launch tower A service structure is a steel framework or tower that is built on a rocket launch pad to facilitate assembly and servicing. An umbilical tower also usually includes an elevator which allows maintenance and crew access. Immediately before ignit ...

, service tower,

service structure A service structure is a steel framework or tower that is built on a rocket launch pad to facilitate assembly and servicing. An umbilical tower also usually includes an elevator which allows maintenance and crew access. Immediately before igniti ...

scaffold Scaffolding, also called scaffold or staging, is a temporary structure used to support a work crew and materials to aid in the construction, maintenance and repair of buildings, bridges and all other man-made structures. Scaffolds are widely used ...

tower crane A crane is a type of machine, generally equipped with a hoist rope, wire ropes or chains, and sheaves, that can be used both to lift and lower materials and to move them horizontally. It is mainly used for lifting heavy objects and transpor ...

. * To access atmospheric conditions aloft:

wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each yea ...

, meteorological measurement tower, tower telescope, solar power station * To lift high tension cables for electrical power distribution

transmission tower A transmission tower, also known as an electricity pylon or simply a pylon in British English and as a hydro tower in Canadian English, is a tall structure, usually a steel lattice tower, used to support an overhead power line. In electrical ...

* To take advantage of the temperature gradient inherent in a height differential: cooling tower * To expel and disperse potentially harmful gases and particulates into the atmosphere: chimney * To protect from exposure: BREN Tower, lightning rod tower * For industrial production:

shot tower A shot tower is a tower designed for the production of small-diameter shot balls by free fall of molten lead, which is then caught in a water basin. The shot is primarily used for projectiles in shotguns, and for ballast, radiation shielding, ...

* For surveying: Survey tower * To drop objects: Drop tube (drop tower),

bomb tower A bomb tower is a lightly constructed tower, often 100 to 700 feet (30 to 210 meters) high, built to hold a nuclear weapon for an above ground nuclear test. The tower holds the bomb for the purpose of the investigation of its destructive effects ...

diving platform A diving platform or diving tower is a type of structure used for competitive diving. It consists of a vertical rigid "tower" with one or more horizontal platforms extending out over a deep pool of water. In platform diving, the diver jumps from ...

* To test height-intensive applications: elevator test tower * To improve structural integrity: thyristor tower * To mimic towers or provide height for training purposes:

fire tower A fire lookout tower, fire tower or lookout tower, provides housing and protection for a person known as a " fire lookout" whose duty it is to search for wildfires in the wilderness. It is a small building, usually on the summit of a mountain or ...

, parachute tower * As art:

Shukhov Tower The Shukhov Radio Tower (russian: Шуховская башня), also known as the Shabolovka Tower (), is a broadcasting tower deriving from the Russian avant-garde in Moscow designed by Vladimir Shukhov. The free-standing steel diagrid st ...

* For recreation: rock climbing tower * As a symbol: Tower of Babel, The Tower (Tarot card), church tower The term "tower" is also sometimes used to refer to firefighting equipment with an extremely tall ladder designed for use in firefighting/rescue operations involving high-rise buildings.

Gallery

References

External links

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