The Hong Kong-Zhuhai-Macao Bridge is finally opening, nine years after construction began.
The $28 billion bridge connects Hong Kong and Macau to the mainland Chinese city of Zhuhai, and is the longest sea-crossing bridge ever built.
But the bridge was supposed to be opened as long ago as 2016, but repeated delays mean the bridge will open to public traffic tomorrow, two years later than planned.
China's President Xi Jinping is expected to attend a ceremony in Zhuhai to mark the bridge's opening.
Supporters of the project say the bridge will cut journey times between the cities from three hours to 30 minutes.
"With the bridge, the traveling time between Hong Kong and the Western Pearl River Delta region will be shortened significantly, thereby bringing the Western Pearl River Delta region within three hours' drive from Hong Kong," the city's transport secretary, Frank Chan said.
But the bridge has been criticised in Hong Kong.
There are fears the city will be swamped by tourists from mainland China, and also little appetite for greater links to both Macau and Zhuhai.
Critics of the Chinese government see the bridge as a tool to drag Hong Kong closer into Beijing's grip.
"It links Hong Kong to China almost like an umbilical cord. You see it, and you know you're linked up to the motherland," Chinese lawmaker Claudia Mo told CNN earlier this year.
"Hong Kong has had to fund a lot of the bridge, but we won't see many benefits here," she added.
Hong Kong spent upwards $12 million on the project, despite struggling with a lack of public housing, and widespread poverty.