Gustave Eiffel built a secret laboratory at the top of the Eiffel Tower to study weather and aerodynamics.

When the Eiffel Tower was completed in 1889, Gustave Eiffel faced intense criticism from the Parisian artistic elite who called it a 'hollow candlestick.' To justify its existence beyond the 20-year permit, Eiffel transformed the structure into a massive scientific tool. He installed a meteorology lab on the third floor, roughly 276 meters above the ground, equipped with barometers, anemometers, and thermometers.Eiffel collaborated with the Central Meteorological Bureau of France to collect data that was previously impossible to gather from the ground. This research provided the first consistent readings of wind speeds and air pressure at high altitudes in Paris. In 1889, Eiffel famously hosted Thomas Edison in this private apartment and lab, where Edison gifted him a Class M Phonograph. The two spent hours discussing engineering and acoustics while overlooking the city.Beyond meteorology, Eiffel used the tower to conduct pioneering experiments in aerodynamics. He dropped objects from the second level to measure air resistance, eventually publishing 'The Resistance of the Air' in 1913. These experiments were crucial for the early development of aviation and wind engineering. Today, the apartment is a museum exhibit featuring the original furniture and life-like wax figures of Eiffel, his daughter Claire, and Thomas Edison.