A tower viewer is a telescope or pair of binoculars permanently mounted on a stalk. The device magnifies objects seen through its lenses, allowing users to see farther and more clearly than they could with the naked eye or with less powerful viewing devices. Tower viewers are typically metallic and most swivel horizontally and vertically (within given axes of rotation) to permit a range of view. The viewing machines are commonly placed in tourist destinations and scenic lookouts for the purpose of viewing attractions and events of interest; they are also used in residential, business, recreational and government locations for the purposes of surveillance and safety monitoring.
Tower viewers are known by a variety of names, including:
Some machines (such as Hi-Spy Viewing Machines, Inc.) are equipped with speakers that enable listeners to hear audio guides to the attractions within view. Additionally, listeners may select the language they wish to hear.
Tower viewers placed in public locations or used for fundraising purposes may be coin-operated or bill-acceptors; some others are free of charge. When payment is required to operate the machine, the viewing period is specifically timed. In the case of coin-operated Tower Optical viewers, for example, paid viewing times are "roughly 1.5 to 2.5 minutes".
Tower viewers are popularly used worldwide. For example, SeeCoast Manufacturing Company states: "SeeCoast's viewers can be found in every U.S. state and in over 80 overseas locations throughout the world."
Two well-known manufacturers of tower viewers in the United States are Tower Optical Co., Inc. (founded in 1933) and SeeCoast Manufacturing Company, Inc. (founded in 1960). Both firms offer wheelchair-accessible viewer bases that provide easy access to the sighting mechanisms in compliance with the Americans with Disabilities Act.
Tower viewer manufacturers located abroad include Hi-Spy Viewing Machines, Inc. (established in 1991) in Cobourg, Ontario, Canada.