The dome of the Fulton Street Transit Center rises 106 feet above the street. View Full Caption DNAinfo/Julie Shapiro

LOWER MANHATTAN — Inside the future Fulton Street Transit Center, four stories below street level, the sun is shining.

The $1.4 billion subway hub won't open until 2014, but one of its most distinctive features is already in place: a yawning skylight, measuring 53 feet in diameter, which funnels natural light down into the station, brightening the darkest corners, even during the ongoing construction.

Directly beneath the skylight, called an "oculus," a spiral staircase curves around the steel supports for a yet-to-be-installed elevator. The elevator will be made of glass, as will the staircase's railing.

For the MTA staff who have been planning and building the Fulton Street station for more than seven years, the recent progress is thrilling.

A rendering of the glass dome, or oculus, that will top the new station and direct sunlight down to the platforms. View Full Caption Metropolitan Transportation Authority

"It's all coming together," said Uday Durg, the MTA's senior vice president and program executive for Lower Manhattan projects, as he proudly showed off the inside of the station Thursday afternoon.

"It's been a long, tortuous road," Durg added, "but finally I see a light at the end of the tunnel."

The project was nearly derailed three years ago when the MTA ran out of money to complete the station, but the federal government came through with more than $400 million in stimulus funds in 2009, allowing the hub to be built.

Since then, the project has faced many challenges, including propping up the sagging Corbin Building, a historic landmark that was so unstable it sometimes shifted noticeably overnight. The MTA also had to be extremely careful while excavating and driving piles, because much of the project sits below the water table.

"If we do anything wrong, the water is going to come in," Durg said.

When the station at the corner of Fulton Street and Broadway finally opens in the summer of 2014, the MTA envisions it as more than just a hub for commuters to rush between 10 connecting train lines.

"What we're trying to do is create a great public space," Durg said. "We want to make sure it's a positive attraction."

Planned features include large LCD screens with information about train schedules, scrolling messages to direct lost straphangers and high-tech advertising signage that can be switched with the touch of a computer button. The MTA is also lining the entire station with glass, brick-shaped tiles that have never been used before in the subway system, to create a unifying aesthetic.

The station and the Corbin Building, which the MTA is restoring, will contain 70,000 square feet of retail space, including a bar and restaurant overlooking Broadway, St. Paul's Chapel and the rising World Trade Center towers, Durg said.

The MTA plans to issue a request for proposals this spring to find an operator for all of the retail space, Durg said.

Natural sunlight will flood the transit center during the day, thanks to the tall glass-and-steel skylight that is already in place. At night, tiny lights projected onto the glass dome will create the illusion of a starry sky, Durg said.

While the main station building won't open for another 2½ years, the MTA has already begun rolling out new entrances and amenities as they are complete.

This year, the southbound N/R platform at Cortlandt Street reopened after years of construction, and the MTA also opened a new entrance at 135 William St.

"We've made every single milestone," Durg said, noting that the project is on budget and on schedule. "We've kept our promises."

Looking ahead, a new glass-topped entrance to the station will open at Dey Street and Broadway in the summer of 2012, Durg said.

At the same time, the MTA will open a new passageway beneath Dey Street, connecting the Cortlandt Street N/R station to the other Fulton Street lines for the first time.

That passageway along Dey Street will be lined with glass on one side and aluminum on the other, giving a hint of the airy, sparkling station just to the east, Durg said.

"People will start to get the sense," Durg said, "that they're walking toward something spectacular."