When you cross a bridge it usually takes a few seconds. The Danyang–Kunshan Grand Bridge in eastern China takes a high-speed train about 25 minutes to cross. It runs for 102 miles (164 kilometers) across paddies, rivers, lakes and town outskirts, making it the longest bridge on Earth by a huge margin.
It was built so that bullet trains between Shanghai and Nanjing wouldn’t have to slow down for every village, river and field in the way. Instead of carving up the land, engineers lifted the whole railway onto thousands of concrete columns. A train can now zip over it at almost 190 mph.
Building it was a giant Lego project. Workers cast huge concrete beams in a factory, hauled them out one by one, and dropped them onto the columns. With around 10,000 people on the job, the whole bridge was finished in only four years, which is fast for a structure heavier than a small mountain.
