Sydney's new multi-billion-dollar metro line is up and running with government ministers, city workers and train enthusiasts among those aboard the first service.
Crowds eagerly lined the new station platforms on Monday morning to catch a first glimpse of the service between Chatswood and Sydenham.
Services began running from Sydenham station at 4:54am, but some enthusiasts had arrived as early as 1am.
"Finally having a transport line that's fully wheelchair accessible at every station, level access boarding ... is going to be a huge game-changer," a commuter and disability advocate told ABC News.
Commuters in Chatswood also expressed their excitement about the opening.
"I always catch the usual train to Central, but now I got this direct one, it's a faster one," one passenger said.
Another commuter, who took the metro from Sydenham to Chatswood, had taken photos of the opening.
"Taking the historical moment of the Sydney Metro opening from this stage from building to its actual operation is pretty exciting," he said.
"It's made connecting between Chatswood and Central and Sydenham much quicker than the trains before."
Hayley Johnson and Jessica Parsons left Newcastle at 10pm last night to make sure they could ride the first train to Tallawong in Sydney's north-west.
"You really feel your back hit the seat," Ms Johnson said of the speed.
"It's a really cool piece of infrastructure, the architecture of all the stations is beautiful," Ms Parsons added.
'Historic day for Sydney'
Premier Chris Minns said the service would "transform Sydney" and make different parts of the city more accessible to Sydneysiders.
He singled out former Liberal premier Gladys Berejiklian for praise in getting the line built.
"Gladys Berejiklian deserves a lot of credit for this city-shaping piece of infrastructure," he said.
"She had the vision to get it done, it's a great addition to the city and I congratulate everybody responsible for this sparkling piece of public transport infrastructure that will change Sydney for the better."
NSW Transport Minister Jo Haylen last week said the opening was the biggest change to the way the city moves since the Sydney Harbour Bridge.
"This train will be able to carry more people than the harbour bridge and the tunnel combined during the peak hour and really takes the pressure off the rest of the public transport network," she said.
"Thousands of people got onboard this morning, it's been an incredible day for our city and means that more people will be able to choose public transport more often.
"This is a historic day for Sydney, so many people are really excited and its great to see them onboard this morning."
She said there would be a family fun day on Saturday to encourage people to try out the new service.
Mr Minns said while commuters may notice some construction work near the entrances to some of the stations, the metro itself was unaffected.
"A lot of the build on top of the stations are not complete, so that might be commercial or residential [and] that will continue perhaps even for years," Mr Minns said.
"But the actual metro is up and running, completely safe, independently ticked off."
Tens of thousands expected to use metro
The first service of the day on the other end of the line left Tallawong in the city's north-west at 4:38am.
Originally the driverless line only ran from Tallawong to Chatswood, with construction of the new 15.5 kilometre section started in 2017.
The wider service will stop at metro stations throughout the city including Chatswood, Crows Nest, Victoria Cross, Barangaroo, Martin Place, Gadigal, Central and Waterloo before terminating at Sydenham.
Sydney Metro's newest train line runs under the harbour bridge and through the heart of the city.
The extended section of the M1 line is up and running after the opening of the $21.6 billion project was delayed last week due to safety regulator approvals.
More than 37,000 people are expected to use the new service during peak times in the morning, significantly reducing their travel time.
Twenty-one minutes will be saved from Crows Nest to Central, while commuters travelling from Sydenham to Barangaroo will spend 27 minutes less on a train.
These times at Tallawong and Sydenham will continue seven days a week for the first four weeks of operation. Following this, the first train at Tallawong will depart at 4:08am.
Sydney Metro is Australia's biggest public transport project.
The metro rail extension to Bankstown is due for completion in 2025.