The land on which Gatwick Airport stands was first developed as an aerodrome in the late 1920s. The Air Ministry approved commercial flights from the site in 1933, and the first terminal, "The Beehive", was built in 1935. Scheduled air services from the new terminal began the following year. During the Second World War, the airport was taken over by the military and was known as RAF Gatwick. After the war, the airport returned to its civilian capacity. The airport proper was built in the mid-1950s opening in 1956. The airport buildings were designed by Yorke Rosenberg Mardall between 1955 and 1988. In the 1960s, British United Airways (BUA) and Dan-Air were two of the largest British independent airlines at Gatwick, with the former establishing itself as the dominant scheduled operator at the airport as well as providing a significant number of the airport's non-scheduled services and the latter becoming its leading provider of inclusive tour charter services. Further rapid growth of charter flights at Gatwick was encouraged by the Ministry of Aviation, which instructed airlines to move regular charter flights from Heathrow. Following the takeover of BUA by Caledonian Airways at the beginning of the following decade, the resulting airline, British Caledonian (BCal), became Gatwick's dominant scheduled airline during the 1970s. While continuing to dominate scheduled operations at Gatwick for most of the 1980s, BCal was also one of the airport's major charter airlines until the end of the 1970s (together with Dan-Air, Laker Airways and British Airtours). As a result of conditions imposed by Britain's Monopolies and Mergers Commission on the takeover of BCal by the then newly privatised British Airways (BA) at the end of the 1980s, Dan-Air and Air Europe assumed BCal's former role as Gatwick's dominant scheduled short-haul operator while BA continued in BCal's erstwhile role as the airport's most important scheduled long-haul operator. Following the demise of Air Europe and Dan-Air (both of which had continued to provide a significant number of charter flights in addition to a growing number of scheduled short-haul flights at Gatwick) in the early 1990s, BA (having purchased Dan-Air) began building up Gatwick into a secondary hub (complementing its main hub at Heathrow). These moves resulted in BA becoming Gatwick's dominant airline by the turn of the millennium. BA's subsequent decision to de-hub Gatwick provided the space for easyJet to establish its biggest base at the airport and become its dominant airline. From 1978 to 2008, many flights to and from the United States used Gatwick because of restrictions on the use of Heathrow implemented in the Bermuda II Agreement between the UK and the US. The EU–US Open Skies Agreement, which became effective on 30 March 2008, led several airlines to downsize their transatlantic operations at Gatwick in favour of Heathrow. Continental Airlines was the second transatlantic carrier (after American Airlines) to leave Gatwick after it decided to transfer the seasonal Cleveland service to Heathrow on 3 May 2009. US Airways, Gatwick's last remaining US carrier, ended its service between Gatwick and Charlotte on 30 March 2013. This left Gatwick without a scheduled US airline for the first time in 35 years. Before the COVID-19 pandemic, Delta Air Lines announced its intent to launch service between Gatwick and Boston in the summer of 2020, which would have made it the first US airline to service Gatwick since the withdrawal of the US Airways service in 2013, but the massive global travel downturn placed these plans on indefinite hold. In 2021, JetBlue became the first US airline to serve Gatwick since 2013, with services to New York–JFK and Boston. On 17 September 2008, BAA announced it would sell Gatwick after the Competition Commission published a report about BAA's market dominance in London and the South East.