It consists of a 22.9km oversea bridge and a 6.7km undersea tunnel connected by two artificial islands.
The $20bn Hong Kong-Zhuhai-Macau bridge officially opens on Tuesday in a ceremony that Chinese president Xi Jinping is reportedly planning to attend.
More importantly, it is a key component in China's plan for a Greater Bay Area covering 56,500 sq km across 11 cities in south China. Many have questions about how useful the bridge will be, and there are concerns that China's central government might use the bridge as another way to chip away at Hong Kong's independence, as CityLab reports. Local taxis are not allowed on it and only a few private cars will get a permit to cross. Shuttle buses cost $8-$10 for a single trip depending on the time of day.
But some in Hong Kong have questioned the goal of the bridge, saying no-one really needed it and that it's largely an attempt to symbolically bring Hong Kong closer to the mainland. Others say the bridge is another way for Beijing to bind the autonomous administrative regions closer to China.
Built to withstand a magnitude 8 quake, a super typhoon and strikes by super-sized cargo vessels, the bridge incorporates 400,000 tons of steel - 4.5 times the amount in San Francisco's Golden Gate Bridge.
"Xi Jinping's visit to the region also reinforces Hong Kong's role in the cross-border economy approach that China is developing", said Dr. Winnie King, a specialist in Chinese worldwide political economy at the University of Bristol.
While there seems to be genuine excitement about the bridge from shipping and transportation companies, people in Hong Kong have mixed feelings about it. The area is also known for strong typhoons each year and rare marine species including Chinese white dolphins. Seven workers died in constructing the bridge, and another 275 were injured.