If light is the necessary condition of architecture, then glass is its most provocative metaphor. Glass speaks of everything new, transcendent and enlightened. New construction at Ground Zero, and elsewhere, suggests that the metaphoric possibilities of glass and light are more significant than ever.
A first hopeful sign of what is to come was embodied in a temporary memorial at Ground Zero. "Tribute in Light," the first official memorial at the site, consisted of twin nocturnal beams of azure light rising from the footprint of the destroyed towers. The project was conceived and implemented by architects John Bennett and Gustavo Bonevardi of PROUN Space Studio, artists Julian LaVerdiere and Paul Myoda, architect Richard Nash Gould, and lighting designer Paul Marantz. Visible as far away as Pittsburgh from March 11 to April 13, the tribute's essential idea was that the most fitting response to the loss of more than 2,800 souls and the gaping skyline would be a luminous absence, not presence, a void not a solid.
The idealism expressed by glass-clad skyscrapers has been a dominant curtain-wall theme since the 1950s, when production of large sheets of glass became feasible. However, the psychological and physiological effects of great height and light were first exploited by the Gothic cathedral builders, whose dual obsession with height and light parallels that of contemporary skyscraper builders.
Eight hundred years ago, an immensely tall cathedral was the primary way of announcing one's religious and technical superiority. Appeasing God with these marvelous structures was a way of keeping, in those dark ages, the unknown and the uncontrollable at bay. With the advent of the flying buttress came the ability to pierce heavy masonry walls with glorious panels of stained glass. The light that poured in was a metaphor — for enlightenment on earth and the promise of paradise after death.
As the supreme creations of their age, Gothic cathedrals were without peer until a hundred years ago, when they were supplanted by skyscrapers. It didn't take long for corporations to realize that a tall building could serve as a gigantic billboard, effectively drawing a parallel between the superiority of their building technology and that of their products.
The now-extinguished twin beams of the “Tribute in Light” memorial marked the location of the WTC towers.
Windows became increasingly larger as architects moved away from a masonry tradition to the liberating modernity expressed by a glass skin. "Glass has that paradoxical quality of creating boundaries while simultaneously eliminating them," notes George Schieferdecker, a partner with BKSK Architects in New York City.
Suddenly, in the light-spangled constellation that is Manhattan, the perception of skyscrapers was changed on September 11. While the building materials themselves remain essentially unchanged, the high-rise office building is undergoing a reassessment in the public mind. From sand and ashes are rising skyscrapers of glass, also made of sand and ashes.
A completed project and a planned project at the former World Trade Center (WTC) site offer a glimpse of what is to come. The Winter Garden, a grand glass atrium in the adjacent World Financial Center (WFC), will be the first major building destroyed by the collapse of the Twin Towers to reopen — on Sept. 17. Debris destroyed a pedestrian bridge that carried 80,000 people a day from the WTC to the WFC and served as the Winter Garden's main entrance.
Cesar Pelli & Associates, New Haven, Conn., which also designed the original structure, stripped away the granite façade and reconfigured the entrance as an expanse of clear glass panels supported by a minimal structure. On the second level, a 110-ft.-long balcony stretches along the façade's width and provides a viewing space that looks east.
"This time it will have a new and more profound meaning because this public room overlooks Ground Zero, the site that the World Trade Center used to occupy," says Pelli. The design anticipates a wide variety of unknown factors: the extension of Hudson River Park, the sinking of West Street and an expansion of the pedestrian zones in the surrounding area.
Skidmore, Owings & Merrill's (SOM) redesign of the destroyed Seven World Trade Center has been described as a transparent, "light-emanating shaft" that would be "the inverse" of the previous granite and dark-glass structure. The lower 10 floors, which will house the Con Edison substation that also was destroyed, will be cloaked in a decorative, metal grille. The top 42 stories will be sheathed in glass. David Childs, a consulting partner at SOM, said the objective is to "provide the city with a great shaft of light" and compared the building to the "great obelisk leading into Luxor."
The Winter Garden, a grand glass atrium in the World Financial Center adjacent to the World Trade Center site, will be the first building to reopen at Ground Zero.
These new designs for New York buildings mirror international trends by utilizing glass as a primary motif. Plans were announced earlier this year to construct the London Bridge Tower which, at a height of 1,016 feet, would be the tallest in Europe and the first there to break the 1,000-ft. barrier. Designed by Italy-based Renzo Piano and dubbed the "Shard of Glass," the spire pays homage to the church spires that punctuate the London skyline. The project was pending approval by London authorities.
A second London skyscraper, the 600-ft. Heron Tower, was approved in July and may provide the impetus needed to gain a final approval for Piano's project. Designed by Kohn Pedersen Fox, the mixed-use building is distinguished from an earlier generation of tall London buildings by a translucent façade.
An inescapable, exhausting need to mentally re-create the Twin Towers on the skyline continues to exist a year after the September 11 attacks. The pressure to make a symbolic architectural statement at the WTC site is unprecedented in contemporary times. Whatever is built there must foster the ideals expressed by light and glass and offer hope for the future in the face of unknown and uncontrollable forces.