The view from the subway level up into the atrium. Photos: Mike Segar/Reuters

New York’s biggest underground terminus has opened in lower Manhattan – a vital link between the new World Trade Centre and the rest of the city.

The Metropolitan Transportation Authority inaugurated the $1.4 billion Fulton Centre, a space-age complex where nine tube lines converge.

“Welcome to the station of the 21st century,” said engineer Michael Horodniceanu, who led the project as president of the MTA’s Capital Construction.

The hub, which merges century-old stations with the latest digital technology and design, will open to the public this morning, when hundreds of thousands will enter what officials called Lower Manhattan’s “next great public space”.

Its soaring street-level atrium is encased in a glass-and-steel shell, with luminous interior panels leading to a skylight designers call the ‘oculus’ –Latin for eye.

Livening up the climate-controlled, energy-saving spaces are various avant-garde artworks.

But building the hub was fraught with challenges. The five underground stations partly damaged in the terrorist attacks on September 11, 2001, were closed for months. Then, in 2012, Superstorm Sandy caused flood waters to roar into the tunnels, crippling service.

Now, just metres from the revitalised trade centre, the complex is part of a “new hot area”, said Senator Charles Schumer.

It shows you how New York City can always reinvent itself and get better

“It shows you how New York City can always reinvent itself and get better,” he said, remembering the gloomy maze of the old Fulton Street stop where “you would have to rush through those narrow corridors weaving through passengers; everyone is going in every direction, where you could knock someone over or they’d knock you over”.

People walking into the Fulton Centre train station.

The government funded 90 per cent of the cost of the centre and New York state the rest. About $850 million came from a special congressional appropriation in the wake of 9/11.

The old stations that were refurbished and linked were used by more than 80 per cent of the workers commuting to Lower Manhattan.

A 106-metre tunnel links the Fulton Centre to the World Trade Centre’s Santiago Calatrava-designed transport facility being built and the PATH commuter train to New Jersey. That tunnel will open some time next year.

The Fulton project includes the restoration of an early high-rise – the 125-year-old Corbin Building with a sumptuous, nine-storey tower. Its original stone foundation is exposed over a set of Fulton escalators.

The historic building in the new setting brings the neighbourhood full circle to the 19th century “when this was the centre of New York City”, said engineer Horodniceanu.