Due to its geographical location and the fact that it reaches an imposing height of 167 metres from the bottom of the mound, the Tour de Montlhéry has been used on many occasions as a scientific testing ground.
1822 = Calculation of the speed of sound by François Agago, Louis-Joseph Gay Lussac and Urbain le Verrier. They fired a cannon from the top of the Tower, at night so that the detonation could be both seen and heard from Villejuif observatory.
1823 = Telegraph tower visible from Fontenay-aux-Roses and Torfou
1874 = From the very top of the tower, Alfred Cornu measured the speed of light from the Paris observatory.
1914 = The inventor, Defieber, tested his parachute model here.