The Eiffel Tower's lattice design prevents it from vibrating at frequencies humans can feel.

The Eiffel Tower, completed in 1889, is a masterpiece of wind engineering and structural dynamics. Gustave Eiffel used advanced mathematics to determine the specific curvature of the tower's four uprights. This shape ensures that the wind's force is transformed into compression rather than bending tension. This design choice significantly influences the structure's 'natural period,' which is the time it takes to complete one full vibration cycle.According to measurements by the Eiffel Tower's engineering team, the tower has a natural frequency of approximately 0.3 Hertz. This means it takes about 3.3 seconds to complete one sway. Because this frequency is so low, it falls well below the threshold of vibrations that cause human discomfort or motion sickness. In contrast, modern skyscrapers often have higher frequencies that can be more noticeable to occupants.During a massive storm in 1999, wind speeds reached 150 kilometers per hour, yet the tower's peak only shifted about 13 centimeters from its vertical axis. The open lattice structure allows 80 percent of the wind to pass through the building rather than pushing against it. This transparency to wind, combined with the massive 7,300-ton iron frame, creates a damping effect that absorbs energy. These factors combined ensure that the tower remains one of the most stable tall structures in the world.