“We had to do something to show the world that was busy migrating out of lower Manhattan that we were going to rebuild lower Manhattan.… I said, ‘Let’s get this rebuilt. Let’s start the design.’ And that’s exactly what I did.”

LARRY SILVERSTEIN

Seven’s base made unique demands. It had to accommodate a new ConEd substation, after the one housed inside the original Seven World Trade Center was destroyed. The replacement substation contained massive transformers, each weighing about 250,000 pounds (113,398.1 kg) and measuring nearly eighty feet (24.4 m) tall. To reestablish a sidewalk entrance (the previous entrance had been elevated), Seven had to be built around these transformers, which are located on the north and south sides. Complicating matters further, the transformers had to be ventilated and above grade; they couldn’t be lowered into the ground because the land is infill, reclaimed years ago from the Hudson River. These requirements determined the design of Seven’s eighty-two-foot-high (25 m) podium wall, which is sheathed in a double stainless-steel skin with a seven-inch (17.8 cm) internal cavity that permits uninterrupted airflow. The skin’s stainless steel panels are variously angled to catch light, visually complementing the upper crystalline tower. Because the substation precluded putting shops and restaurants on the ground level, the podium scrim was fitted with LED fixtures that cast patterned blue and white light at night. To further animate the lower walls, motion sensors track movement on the sidewalk, displaying vertical bars of colored light as pedestrians walk by. When the new substation opened in May 2004, the beginnings of the new Seven, then about twenty feet (6.1 m) high, rose above it.

Security concerns also determined the design of the entrance. It appears remarkably open and light yet deploys a three-tiered security strategy. The entrance’s cable-net glass wall brings in light but is blast-resistant. Inside the lobby, a protective illuminated ceiling changes in luminosity and color during the day (white) and at night (blue). A glass wall, sixty-five feet (19.8 m) wide and fourteen feet (4.3 m) high, behind the reception desk is actually a cleverly disguised blast shield that protects the elevator lobbies. It is also a work of art: For 7 World Trade is a 2006 installation by artist Jenny Holzer, made in collaboration with Carpenter, which features scrolling snippets of poetry and prose about New York. Carpenter designed the wall, which consists of two layers of glass, between which is suspended the LED system that generates the literary texts. More than a site-specific work, the piece marks the first time artists collaborated on the structural design of a building.

Landscape architect Ken Smith designed the triangular park in front of Seven, formed by the intersection of Greenwich Street and West Broadway. Jetted fountains surround its centerpiece, Jeff Koons’s whimsical Balloon Flower (Red), a stainless steel sculpture on extended loan from the artist.

The entrance’s cable-net glass wall was first developed by SOM, Carpenter, and Schlaich Bergermann for the Time Warner Center and later used at One World Trade Center. On the left is the blast-resistant wall that is an integral part of the Holzer/Carpenter installation.

These diagrams by James Carpenter Design Associates identify the components of Seven’s unique “linear lap” curtain wall system. Sectional diagrams of the spandrel show how the sun’s rays, indicated by the red lines, are redirected during summer and winter. A blue stainless steel reflector on the lower part of the spandrel bounces blue light up onto the curved reflector, enhancing the curtain wall’s color and reflectivity.

With input from others, Seven’s architects and engineers developed safety and security solutions that formed the basis of future high-rise building codes. At the time it was designed, the New York City Building Code, not updated since 1986, was prescriptive. After September 11, the New York City Building Department rewrote the code, although changes governing security and safety would not be incorporated until 2008. SOM made life safety a prominent goal of the building design. Throughout, Silverstein was actively involved, sitting “at the head of the table at every meeting, and follow[ing] everything, including all safety developments proposed for both Seven and One World Trade Center,” Carl Galioto, formerly a technical partner at SOM, said.

Seven’s safety measures largely established—and exceeded—the new code. Its stairwells, twenty percent wider than required, are pressurized and marked with glow-in-the-dark strips so tenants can exit easily and quickly during an evacuation. Leaky coaxial wiring for walkie-talkies allows uninterrupted emergency communications. Enhanced fireproofing material coats columns and floors. Critically, the central concrete core, two feet (0.6 m) thick and running the tower’s full height, contains and protects stairways, elevators, communication systems, water storage, and power sources.

Seven boasts equally impressive environmental features. It was the first building in Manhattan to receive Gold LEED (Leadership in Energy and Environmental Design) certification from the U.S. Green Building Council. Its energy efficiencies include full-length glass windows that maximize daylight, high-performance HVAC and plumbing systems, and rooftop rainwater collection. Even the tenant leases are green: In 2011, Seven’s leases became the first to incorporate groundbreaking language that allows owners and tenants to share the costs and benefits of sustainable improvements. The tower was fully leased by 2011.

“We were collaborative for months and months. That normally doesn’t happen.… This was much more intimate, much more moment-to-moment and probably the best experience of the sort that I’ve ever had.”

PETER WALKER on working at Silverstein’s offices, 2014

This photo commemorates the unveiling of the designs for three new Trade Center towers on September 7, 2006. Developer Silverstein (red tie) is pictured with his architects (left to right): Fumihiko Maki (4WTC), Norman Foster (2WTC), and Richard Rogers (3WTC). In 2015, Bjarke Ingels Group (BIG) was tapped to produce a new design for Two World Trade Center.

Seven also served as the design headquarters for Two, Three, and Four World Trade Center. Silverstein created an atelier on the tenth floor, where upward of two hundred people worked daily in one large room. This arrangement, an unprecedented collaboration, was a classic Silverstein move—brilliant yet practical. Having the towers’ architects and engineers in the same room, along with those who would make sure the buildings met city and state planning requirements, made the work proceed more efficiently and helped avoid costly design changes. There was never a danger of design uniformity—the artistic egos involved guaranteed that—or of an aesthetic free-for-all that would undermine a visually cohesive site. Instead, there was a fusion of sensibilities that Times reporter David Dunlap aptly likened to the harmony of a “jazz quartet.”