The board of the Port Authority voted yesterday to approve a design for the World Trade Center transportation hub by architect Santiago Calatrava.

In eulogizing the $2.21 billion project, board members, and Mr. Calatrava, imbued the building with a “transcendental” power, where form married to function could simultaneously pay homage to the legacy of the now-hallowed 16-acre site while also stimulating commerce and luring back tenants who have long ago moved across the Hudson River.

For the board members, whose chief concern is commerce, the watchwords were “restore,” and “rebuild.” To return Lower Manhattan to its pre-September 11, 2001, status, though, required something unseen during the era of the World Trade Center: a transportation infrastructure that would connect PATH train commuters with the city’s subways, ferries, and financial district. The transit hub will also be equipped to one day receive Long Island Rail Road trains and a rail link to John F. Kennedy airport.

When the board voted to approve the design, which will be paid primarily with $1.92 million from the Federal Transit Administration, though the board has committed $221 million of its own money, its members began stumping for it.

Mr. Calatrava’s design is nonetheless a scaled-back version of the original idea presented in January 2004. Owing to security concerns, the white-colored building, which looks something like the skeleton of a stegosaurus, has extra ribs and an elongated prow to fortify the structure’s openings. The building’s open design is its greatest security asset, allowing for clear views for those who will be assigned to keep a watchful eye over it.