Gatwick Airport, West Sussex, UK, aerial photograph. Gatwick acts as London's second airport (after Heathrow), despite being some 40 kilometres from the city. It only has one runway, and is the busiest single-runway airport in the world. It has been operating as an airport since the 1930s, but only as a commercial alternative to Heathrow since the Second World War. It was renovated in the mid-1950s and reopened in 1958. The North Terminal (upper centre) was added to the South Terminal in 1988. The two are linked by a monorail (pale brown line running from centre to right).