The Q121 wind tunnel, located in Farnborough, southwest of London, is a massive structure built between 1931 and 1935. It was once one of the largest wind tunnels in the world, measuring approximately 70 meters long, 43 meters wide, and 15 meters high, constructed from steel and reinforced concrete. The tunnel was designed to withstand enormous mechanical stresses, as its 9-meter diameter fan, equipped with six laminated walnut blades, could propel air at speeds up to 185 km/h, creating a controlled air cylinder of more than 7 meters in diameter. The installation was nicknamed the "24 foot wind tunnel" due to this controlled column of air. The wind tunnel was officially inaugurated on April 4, 1935, with the first aircraft tested being a Gloster Gauntlet equipped with a Bristol Mercury engine. This choice was not accidental, as Farnborough, through its Royal Aircraft Establishment, was emerging as a key center for British military aeronautical research. Over the decades, the Q121 wind tunnel played a significant role in the evolution of British combat aviation, notably being used to refine the aerodynamics of the Hawker Hurricane, a fighter that played a decisive role in the Battle of Britain. Its use continued throughout the Cold War, with many British bombers and fighters undergoing real-scale testing at the facility. The wind tunnel ceased all activity in 1994, a victim of its energy consumption of 10 megawatts and the rise of numerical simulations replacing physical tests. The motors of the wind tunnel consumed no less than 10 megawatts of electricity, a power comparable to that needed to supply several thousand homes simultaneously, all to produce airflows reaching up to 400 km/h in its most extreme configurations. Such energy consumption, combined with the rapid rise of computing and aerodynamic simulation software, eventually rendered the installation obsolete. Gradually, engineers abandoned real-scale physical tests in favor of numerical modeling, which was much more economical and faster to implement. The Q121 wind tunnel thus ceased all activity in 1994, without any aircraft or model ever being retested there since. In 1993, the British Ministry of Defense considered demolishing and selling the former site of the Royal Aircraft Establishment. The building narrowly escaped destruction, saved for posterity thanks to its exceptional architectural and technical interest. Today, Q121 is classified as Grade I by Historic England, the highest level of heritage protection in the United Kingdom, on par with some of the country's most emblematic monuments. The site, along with the neighboring R52 building dating from 1917, even opened its doors to the public for the first time in 2014, coinciding with the famous Farnborough air show, as part of an art installation. A way to reintroduce visitors to this place that had remained dormant for more than fifty years. But outside of these rare interludes, the wind tunnel remains frozen, intact, as if suspended between glorious past and uncertain future.