Taken from the NYTimes.com

The architect Craig Dykers has been working since 2004 on the design of a museum building for the World Trade Center site. In the end, he realized there could be no more powerful a centerpiece than something Minoru Yamasaki designed 45 years ago.
To an otherwise Spartan design for the twin towers, Mr. Yamasaki, the original architect, added one instantly recognizable flourish: trident shaped columns at the base of the buildings, which created an arcade of almost Gothic proportion. Enough of these enormous steel tridents survived the terrorist attack of Sept. 11, 2001, that their familiar silhouettes came to symbolize endurance in the face of catastrophe.
Two surviving tridents from the north face of the north tower, each almost 90 feet tall, will return to ground zero to be incorporated in the atrium of the museum pavilion designed by Mr. Dykers and his colleagues in the firm Snohetta, which is based in Oslo and New York. This, the latest of several designs for a cultural building at ground zero, was unveiled on Tuesday as the seventh anniversary of 9/11 approached.
“The two tridents placed side by side will create an immediate visual reference to the distinctive ‘Gothic arch’ motif of the twin towers,” Snohetta said in a statement of its architectural intentions, “and, in their re-erection at the site, will convey strength, fortitude, resilience, survival and hope.”
The pavilion will serve as the entrance to the subterranean exhibition galleries of the National September 11 Memorial and Museum at the World Trade Center. As the only part of the museum that is above ground, the pavilion will be highly visible from the surrounding streets and from the landscaped memorial plaza and pools that will wrap around it on three sides.
Advance copies of the designs were distributed under an embargo that was lifted with an official unveiling this morning. The briefing is still under way.
Though the broad outlines of the design have been known for some time, the unveiling on Tuesday provided and confirmed some key details about the $80 million pavilion, which is being financed by New York State. The polygonal pavilion will range in height from 57 to 72 feet (roughly equal to a six-story office building). It will contain 47,499 square feet of floor area; 34,834 square feet devoted to public programs and museum functions, the rest to ventilating ductwork and mechanical equipment serving the underground museum, the nearby World Trade Center Transportation Hub and the No. 1 subway line.
The ground floor will have ticket windows, a large security area in which visitors will undergo airport-style screening, and a staircase, escalators and elevators down which they will begin a trip that will lead them nearly 70 feet below street level, ending near an exposed part of the slurry wall. There will also be exit doors ushering them into the heart of the memorial plaza.
On the second floor will be a 180-seat auditorium, a private room in which relatives of 9/11 victims may gather, an overlook from which visitors can take in a sweeping view of the memorial, and a small cafe. (“For sustenance,” Mr. Dykers said, “not a restaurant per se.”)
The third floor will be given over entirely to equipment and ventilation.
The museum is to open in 2012, a year after the memorial plaza. It is not yet known whether an admission fee will be charged. Museum officials have estimated the annual maintenance cost of the memorial and museum at $45 million to $50 million. “If we can get the money from other sources, we won’t charge,” said Joseph C. Daniels, the president and chief executive.
About five million visitors are expected annually, said Alice M. Greenwald, the museum director. The building is designed to handle 1,500 people arriving an hour, she said.
Snohetta’s involvement at the site dates to 2004, when the firm was selected to design a museum complex that was to have included the Drawing Center from SoHo and a new institution known as the International Freedom Center. That plan collapsed in 2005. Snohetta then began working on a much smaller structure to serve as the museum’s front door.
The current plans call for the pavilion to be clad largely in metal panels — stainless steel, if the budget permits; aluminum if not. The panels will be angled and striated, with alternating bands of polished and matte finish. The design is intended, in part, to add visual interest, especially to the south facade of the building, which would otherwise be a blank wall punctuated by ventilating louvers, since so much mechanical equipment is on that side.
In the northwest corner will be an atrium, running the height of the building and enclosed in an angular framework of glass and steel. This will house the tridents, which are currently stored in a hangar at Kennedy International Airport, and allow them to be seen from within the museum and from around the plaza — especially after dark, when they will be illuminated.
“When they’re lit at night, they will guard the site,” Ms. Greenwald said. “They’re like sentries.”
The large glass enclosure had to be robust enough structurally to withstand the effects of a blast. Among other criteria, glass expanses could be no wider at any point than 15 feet. (Architects and engineers never specify publicly exactly how blast-resistant such features are, for fear that terrorists will use that information to overcome the structural reinforcements.)
The framework had to be supported on irregularly spaced columns below ground. And Mr. Dykers said he did not want the window wall to have purely vertical elements, which would come into conflict visually with the upright tridents.
A computer was harnessed to plot the most efficient locations for the structural members of the framework. The result, designed by Snohetta and the engineers of Buro Happold, is a pattern that looks organic and weblike, reminiscent of some of the earliest designs for the trade center site by Daniel Liebeskind.
From certain perspectives, it might also suggest an explosion, with random, irregular shapes that could be seen as flying shards. No such imagery was consciously intended by the architects, Mr. Dykers said, though he added that the design is not meant to shy away from the “dualities” inherent in the new trade center, which will be a place both of mourning and of hope.
Ms. Greenwald suggested there was no wrong way for visitors to view the memorial pavilion.
“Because 9/11 was so much a lived experience,” she said, “they will bring their own interpretations to the site. And that’s very powerful.”
And though no attempt was made to use the tridents to replicate the towers’ facades, she also suggested that they will ultimately serve a kindred function at the memorial. “They will become a kind of compass point,” Ms. Greenwald said, “no matter where you are.”