The Eiffel Tower Can Be 15 Centimeters Taller in Summer

Sound travels at approximately 343 m/s in air at 20°C, but reaches about 1,484 m/s in seawater — over 4 times faster. Water's greater density and incompressibility allow molecules to transfer vibrations more efficiently. This is why humpback whales can communicate over thousands of kilometers through the ocean.

Steel expands when heated. During hot summer days, the iron lattice of the Eiffel Tower can expand enough to grow approximately 15 cm in height. In winter, the cold causes the metal to contract and the tower shrinks back down.

The Forbidden City in Beijing, built between 1406 and 1420, was the imperial palace of 24 Ming and Qing dynasty emperors. It contains approximately 8,728 rooms across 180 acres and is the world's largest palace complex. Forbidden to ordinary citizens for 500 years, it is now China's most-visited museum, drawing over 14 million visitors annually before the COVID-19 pandemic.

The Three Gorges Dam on the Yangtze River is the world's largest hydropower facility by installed capacity, generating up to 22,500 megawatts. Completed in 2003 with full capacity reached by 2012, it required the relocation of over 1.3 million people. The dam provides flood control, navigation improvements, and roughly 1.7% of China's total electricity supply.