A rare Blow-Knox Radiator diamond-shaped broadcast tower still in use
WSM-AM was designated as a "clear channel" station in the United States, listed by the FCC in 1938.
The tower is located south of Nashville, just off I-65 and can be seen from Tower Park. WSM-AM has been broadcasting the world-famous Grand Ole Opry from this tower since 1925 (when it was called The WSM Barn Dance.) The Grand Ole Opry moniker was coined by host "Judge" George D. Hay in 1927. It is the longest continuous radio program in history.
The main building is Colonial Revival designed by Russell Hart of Hart, Freeland, and Roberts. There are some secrets to the complex. In World War II, the tower was designated as a communications device for American submarines in the event traditional radio communications were lost. WSM-AM was one of the original stations in the CONELRAD system beginning in 1951. There is a studio in the basement that was to be used in the event of a military need.
The diamond-shaped tower is such an icon that it was incorporated into the design of the County Music Hall of Fame. The tower is a National Engineering Landmark and was listed on the National Register of Historic Places on March 15, 2011.
* - Today it is known that the optimum height for AM broadcasting of a Class A signal on that frequency is 810 feet. The FCC defines a Class A station as "...an unlimited time station (that is, it can broadcast 24 hours per day) that operates on a clear channel."