Nearly a decade after construction first kicked off, China finally opened its Hong Kong-Zhuhai-Macau bridge on Monday—the world’s longest sea crossing bridge. With a price tag of about $20 billion, the bridge spans 34 miles and connects Hong Kong to Macau and the Chinese city of Zhuhai. The project was plagued by numerous delays and at least 18 workers died constructing the bridge, according to the BBC. Critics have warned that it threatens to bring semi-autonomous Hong Kong further under the control of Beijing. “It links Hong Kong to China almost like an umbilical cord. You see it, and you know you’re linked up to the motherland,” lawmaker Claudia Mo told CNN. Built with 400,000 tons of steel—nearly five times the amount in the Golden Gate Bridge—it was designed to withstand extreme weather like earthquakes and typhoons. The bridge will be open to traffic starting Wednesday, though private cars will need to get special permits to use it, according to the South China Morning Post.