Because heat expands the metal, the Eiffel Tower always leans away from the sun.
The Eiffel Tower Leans Away From the Sun Every Day
The Eiffel Tower isn't just standing still. Every sunny day in Paris, the iconic iron structure performs a subtle dance, leaning away from the sun as if trying to escape the heat. This isn't some architectural quirk—it's pure physics in action.
When sunlight hits one of the tower's four sides, the metal heats up and expands. But here's the catch: only one face gets the full blast of sunshine while the other three remain relatively cool in the shade. This uneven heating causes the sunny side to grow slightly longer than its shaded companions, creating an imbalance that makes the entire 330-meter structure tilt away from the heat source.
The Tower's Daily Journey
On a clear day, the top of the Eiffel Tower doesn't just lean once—it traces a circular path roughly 15 centimeters in diameter as the sun moves across the sky. That's about the width of a smartphone, swaying hundreds of feet in the air. The lean can reach up to 18 centimeters at its maximum, all because one side is basking in sunshine while the others stay cool.
After sunset, the tower gradually straightens out as temperatures equalize. By morning, it's ready to start the whole cycle again.
Summer vs. Winter Height
The seasonal difference is even more dramatic. Between the coldest winter days and the hottest summer afternoons, the Eiffel Tower grows 12 to 15 centimeters taller. This is thermal expansion at work on a grand scale—7,300 tons of puddled iron stretching skyward when the mercury rises.
Gustave Eiffel, the tower's designer, knew all about this when he built the structure in 1889. Engineers calculated every rivet and beam to accommodate these thermal movements. The tower was designed to flex, not fight physics.
Why Iron Moves
Iron's coefficient of thermal expansion means it grows about 12 millionths of a meter for every degree Celsius increase. Multiply that tiny change across a 300-meter tower, and those millionths add up fast. The difference between a chilly 0°C winter night and a scorching 40°C summer day? Those 15 centimeters that make headlines.
Other metal structures experience this too, but few are as tall or as closely monitored as the Eiffel Tower. Engineers regularly measure these movements to ensure the structure remains safe—and after more than 135 years, it's still performing exactly as designed.
So next time you see photos of the Eiffel Tower, remember: it's probably leaning slightly in the opposite direction of the sun, engaged in an eternal game of thermal tag that will continue as long as Paris has sunny days.