Danyang-Kunshan Grand Bridge, China

The Danyang-Kunshan Grand Bridge, China, is the longest bridge in the world at exactly 164.8 km, far surpassing the 36.7 km Lake Pontchartrain Causeway, the second-longest bridge globally. Completed in 2010 using 450,000 tonnes of steel and 2.3 million cubic metres of concrete, its $8.5 billion construction cost remains 60% lower per kilometre than the average high-speed rail viaduct. This viaduct carries the Beijing-Shanghai High Speed Railway over rice paddies, rivers, and Lake Yangcheng, and was built in just four years by a workforce of 10,000. Its length alone outperforms #10 by over 160 km, making it an engineering marvel of scale and efficiency.