World Trade Center transit hub preview

If you've been to Lower Manhattan in the last couple of years you've no doubt seen the striking bird-like exterior of the World Trade Center transportation hub take shape. But now for the first time, here is a look inside as the main concourse, known as the Oculus, prepares to open to the public in March.

The bright white structure, designed by Spanish architect Santiago Calatrava to evoke a bird taking flight, will link the PATH train and 11 subway lines, and house more than 100 restaurants and high-end stores set to open later this year.

The hub's impressive design comes with a hefty $3.9 billion price tag and years of delays. In fact, at one point officials promised the center would open in 2009.

Inside the hub, the floors and platforms are all made of shiny white marble. And slivers of one world trade center can be seen through the windows of the Oculus.

There is more to this grand design than initially meets the eye. Take the roof. The panels actually retract and open. They'll open every September 11 at 10:28 in the morning to commemorate the falling of the Twin Towers.

While a big portion of the center and one entrance will be open in March, there is still much more work to be done. All four main entrances are set to be open by the summer.