Observation tower
Observation towers are usually at least 20 metres (66 ft) tall and are made from stone, iron, and wood.
Similar instances of observation towers are recognised as crow's nests, observatories, viewing platforms, etc.
Observation towers are an easily visible sight on the countryside, as they must rise over trees and other obstacles to ensure clear vision.
Modern towers frequently have observation decks or terraces with restaurants or on the roof of mountain stations of an aerial ropeway.
In particular prior to World War I rambler associations, and some municipalities, built observation towers on numerous summits.
Modern observation towers are in most cases no longer built of brick, but concrete, steel and wood are used as the preferred building materials.
Strictly speaking, control towers also fall into this category, although surveillance from these structures is mostly done in a non-optical way using Radar.
Active watch towers are not as a rule accessible to the public, since they usually serve for the monitoring of sensitive ranges.
A condition for this is a sufficiently stable construction, which permits a permanent safe visitor entrance without interruption of the transmission services.
However this shifted direction of main beam of transmitter away from actual supply area, the city of Berlin.
Prospect outlooks on TV towers are opened only at certain times and their entrance is possible only under payment of an admission fee.
As a rule access usually requires the payment of an admission fee, is possible by elevator only at dedicated opening times.
In addition, there are other sports facilities with observation decks, like the inclined tower of the Montreal Olympic stadium.
Access to the platform of nearly all sports facilities with observation deck is only possible during opening times after paying an admission fee.
Areas where birdlife congregates are often associated with bird observation towers to assist with viewing.
Examples for this are the Henninger Turm, a grain silo with tower restaurant and observation deck in Frankfurt, the bell tower of Berlin Olympic stadium, whose platform is accessible by an elevator, the winding tower of the mining industry museum in Bochum, which has an open-air observation deck to which an elevator runs or a wind turbine in Holtriem wind park, which is equipped with a closed platform accessible over stairs.
Even on the pylons of suspension bridges were already observation decks installed, as the example of Nový Most in Bratislava shows.
In Austria and Switzerland many observation towers were established by alpine and tourist associations, and continue to be cared for by them.
After World War II, a great need for tall observation towers arose, due to their dual usage as television and radio transmitters.
