The Eiffel Tower gets taller in summer.

The Eiffel Tower can stand about 12–15 centimetres taller on the hottest summer days than on cold winter days. The tower is about 300 metres high, so a small change in the length of its iron becomes measurable. Thermal expansion happens because heating increases the average distance between atoms in a material. Sunlight can warm one side more than the other, causing a slight sideways curve away from the sun. 12

Hot iron expands. Cold iron contracts.