Towers or other elevated buildings located at large and medium-sized airports and from which the movement of aircraft and other surrounding traffic is controlled by radio or other means. The control tower structures generally rise high above other buildings at an airport and have windows, tilted outward to avoid glare, circling the entire top floor to allow a clear view for air traffic controllers. They contain necessary equipment, such as radios, radar displays, computer systems for meteorological information and flight data, controllers' headsets, telephone systems, light guns for communication with aircraft via aviation light signals, and wind and pressure gauges.

Source: AAT 

http://vocab.getty.edu/page/aat/300007765