New York ? The first destroyed skyscraper to be rebuilt since Sept. 11 opened Tuesday but attracted few tenants, despite offering state-of-the-art safety features that developers say will be part of all office towers to rise at the World Trade Center site.

Developer Larry Silverstein officially opened the 52-story 7 World Trade Center for business by unveiling a sculpture outside the building and hosting a concert featuring Lou Reed and Suzanne Vega.

“We’ve come a very long way,” said Silverstein, who built the first 7 World Trade Center nearly 20 years ago and has struggled to rebuild destroyed office space at the 16-acre site for more than four years. “What you’re looking at today is just the beginning.”

7 World Trade Center, right, the last building to collapse as a result of the World Trade Center attacks on Sept. 11, 2001, is the first to be permanently rebuilt. The building officially opened Tuesday.

The building at 7 World Trade Center was the third to collapse on Sept. 11, 2001, after the twin towers.

The shimmering glass tower was redesigned by David Childs, the same architect who designed the yet-to-be-built 1,776-foot Freedom Tower, which is intended as the replacement to the trade center.

Including 7 World Trade Center, the trade center site lost more than 10 million square feet of office space on Sept. 11. But new tenants have not been clamoring to return. Silverstein has rented less than a fifth of 7 World Trade’s 1.7 million square feet.

Following recommendations to make high-rises safer after the terrorist attacks, the skyscraper adheres to “a set of standards unique to any high-rise office building in America,” Silverstein said.

The building is narrower and lets in more sunlight than its original version. It is the first commercial tower in New York City to be certified as “green” by the U.S. Green Building Council because it uses less electricity and has high-efficiency cooling and heating systems.

And it has adopted newer safety standards, with wider stairwells and 2-foot-thick concrete walls.