Croydon Airport was the UK's only international airport during the interwar period. Located in Croydon, Surrey, England, it opened in 1920, built in a Neoclassical style, and was developed as Britain's main airport, handling more cargo, mail, and passengers than any other UK airport at the time.
Croydon was the first airport in the world to introduce air traffic control, a control tower, and radio position-fixing procedures. The "aerodrome control tower", 4.6 m high with windows on all four sides, was commissioned on 25 February 1920 and provided basic traffic, weather and location information to pilots. Air traffic control was first developed here, as was the "Mayday" distress call.
Under the provisions of the Croydon Aerodrome Extension Act 1925, the airport was greatly enlarged between 1926 and 1928, with a new complex of buildings being constructed alongside Purley Way, including the first purpose-designed airport terminal and air traffic control tower, the world's first airport hotel, and extensive hangars
In 1978, the terminal building and Gate Lodge were granted protection as Grade II listed buildings. In May 2017, Historic England raised the status of the terminal building to Grade II*. Owing to disrepair, the Gate Lodge is now classified as Heritage at Risk by Historic England.
Much of the site has been built over, but some of the terminal buildings near Purley Way (the A23 road) are still visible, clearly identifiable as to their former purpose. The former terminal building is called Airport House, and the former control tower houses a visitors' center.
According to Wikipedia