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 A guy-wire, guy-line, guy-rope, or stay, also called simply a guy, is a tensioned cable designed to add stability to a free-standing structure. They are used commonly for ship masts, radio masts, wind turbines, utility poles, and tents. A t ...

and are therefore, along with tall buildings, self-supporting structures. Towers are specifically distinguished from

building A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and fu ...

s 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

ziggurat A ziggurat (; Cuneiform: 𒅆𒂍𒉪, Akkadian: ', D-stem of ' 'to protrude, to build high', cognate with other Semitic languages like Hebrew ''zaqar'' (זָקַר) 'protrude') is a type of massive structure built in ancient Mesopotamia. It has ...

s, which existed in Sumerian architecture since the 4th millennium BC. The most famous ziggurats include the Sumerian

Ziggurat of Ur The Ziggurat (or Great Ziggurat) of Ur ( Sumerian: "Etemenniguru", meaning "temple whose foundation creates aura") is a Neo-Sumerian ziggurat in what was the city of Ur near Nasiriyah, in present-day Dhi Qar Province, Iraq. The structure ...

, 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 house A tower house is a particular type of stone structure, built for defensive purposes as well as habitation. Tower houses began to appear in the Middle Ages, especially in mountainous or limited access areas, in order to command and defend strateg ...

s. 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 Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *'' Epistle to the Romans'', shortened to ''Romans'', a lette ...

cultures emphasised the use of a tower in fortification and sentinel roles. For example, the name of the Moroccan city of

Mogador Essaouira ( ; ar, الصويرة, aṣ-Ṣawīra; shi, ⵜⴰⵚⵚⵓⵔⵜ, Taṣṣort, formerly ''Amegdul''), known until the 1960s as Mogador, is a port city in the western Moroccan region of Marakesh-Safi, on the Atlantic coast. It ha ...

, 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 in 210 BC during the Qin Dynasty. Towers were also an important element of Towers in medieval fortifications, castles. The Eiffel Tower, Paris, France

Other well known towers include the Leaning Tower of Pisa in Pisa, Italy built from 1173 until 1372, the Two Towers, Bologna, 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 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 skyscrapers, skyscraper) have 'tower' in their name or are colloquially called 'towers'. Skyscrapers are more properly classified as 'buildings'. In the United Kingdom, tall domestic buildings are referred to as tower blocks. In the United States, the original World Trade Center (1973–2001), World Trade Center had the nickname the Twin Towers, a name shared with the Petronas Twin Towers in Kuala Lumpur. 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, or rolled near a target (see siege tower). 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 or a water tower, or aim an object into the earth such as a drilling tower. ski jumping, 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 box, signal towers and minarets were used to communicate information over greater distances. In more recent years, radio masts and cell phone towers facilitate communication by expanding the range of the transmitter. The CN Tower 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 bridges. 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, service tower, service structure, scaffolding, scaffold, tower crane. * To access atmospheric conditions aloft: wind turbine, meteorological measurement tower, tower telescope, solar thermal energy, solar power station * To lift high tension cables for electrical power distribution transmission tower * 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 * For surveying: Survey tower * To drop objects: Drop tube (drop tower), bomb tower, high diving, diving platform * To test height-intensive applications: Express Lift Tower, elevator test tower * To improve structural integrity: thyristor tower * To mimic towers or provide height for training purposes: fire tower, parachute tower * As art: Shukhov Tower * For recreation: rock climbing, rock climbing tower * As a symbol: Tower of Babel, The Tower (Tarot card), steeple, 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

{{Authority control Towers, sq:Kulla