NEW YORK — The gleaming World Trade Center rising from Ground Zero in New York will be more sophisticated and impressive than the destroyed Twin Towers it replaces, project leaders said Thursday.

"When the buildings are built we will look back at them and say these are a vast improvement on what was there originally," Larry Silverstein, the World Trade Center developer, told journalists.

After years of delays, the principal building, Tower One, is now a stunning sight, with 76 of the eventual 104 floors built, and that number expected to be in the 80s by the 10th anniversary of the September 11, 2001 terrorist attacks.

The sleek, awe-inspiring Twin Towers used to lord over the New York skyline and their collapse after being hit by hijacked airliners was part of a national trauma that went beyond the mourning for the nearly 3,000 people killed.

The four-tower complex now taking shape will look entirely different, with an emphasis on state-of-the-art environmentally friendly architecture, retail space, transport links, and security.

The head of the Port Authority of New York and New Jersey, which owns the site, said the new towers would look to the future and an increasingly residential, revitalized lower Manhattan, rather than make a point about 9/11.

"We had to restore what makes New York City," Port Authority Director Chris Ward said. "Soaring, beautiful office buildings is what New York needs... It didn't need at this point a symbol, a message."

The new World Trade Center, he said, "is not a symbol, it's a site."

Balancing that cool-headed approach is a memorial to the dead that will be open in time for the 9/11 anniversary ceremonies next month to be attended by President Barack Obama and his predecessor, George W. Bush.

The memorial consists of two huge, granite-lined pits, each one occupying the exact location of the foundations of the fallen Twin Towers. Water cascades from the rim into the square pit, then disappears down a smaller, dark square in the center, and the names of all the dead from that day are etched in bronze above.

Silverstein said the whole World Trade Center -- one of the biggest and most complex building projects in existence -- would be finished by 2016.