On any given day, the World Trade Center plaza is jammed with people, most of them oblivious to the unstinting, largely invisible efforts that have been taken to protect them. The Port Authority’s overarching goal was to create public areas that are lively, hospitable, and terrorist-proof and that would “reintegrate this development back into the community. That was first and foremost,” says Port Authority architect Carla Bonacci, whose office developed the plaza’s overall plan and the materials palette for the streetscape and commercial buildings.

Half of the plaza’s sixteen acres (6.5 ha) are devoted to the 9/11 Memorial. The Port Authority and Davis Brody Bond, the associate architect for the National September 11 Memorial & Museum, coordinated with multiple agencies to integrate the underground infrastructure with an aesthetically pleasing experience above ground. The Downtown Streetscape Partners, a joint venture of AECOM and Jacobs, Inc., designed the streetscape elements, street elevations, and the utility infrastructure.

To differentiate it from the rest of the city, the streetscape incorporates elements with a distinctive scale, made of unique materials. This is most evident in the sidewalks, which are twenty-five feet (7.6 m) wide, almost twice as wide as those in the rest of Manhattan, and made of Mesabi Black granite rather than the concrete used elsewhere in the city. These extra-wide walkways, coupled with bollards, sally ports, and guard booths, are security measures but also have the happy benefit of giving pedestrians more room. To integrate the security features, the designers “thought of them as part of the vocabulary of the streetscape furnishings,” said landscape architect Andrew Lavallee, who, with Joseph E. Brown, led the streetscape design effort. “We worked hard to ensure that the booths didn’t suddenly interrupt the free pedestrian flow. The booths landed on islands, or we bumped out the curbs, so we didn’t compromise pedestrian experience for security.” Although it was more costly to locate parking spaces and loading docks below the plaza, doing so significantly improved the appearance and accessibility of the public realm.

Paradoxically, light can only be perceived in the context of darkness, which makes it a potent metaphor for the Trade Center, where contradictory human impulses—to build up or tear down—had to be reconciled. Paul Marantz’s zest for both light and darkness has made him one of the most respected practitioners of the ephemeral art of lighting design. Along with his colleagues at Fisher Marantz Stone (FMS), he has lit a large number of architectural projects around the world. The firm’s involvement at the World Trade Center dates back to 2002, when they realized the lighting for Tribute in Light, the twin beams that shine annually on September 11. They devised lighting for every structure at the Trade Center, with the exceptions of One World Trade Center and the St. Nicholas National Shrine.

The lighting designers had to consider aesthetics as well as security. The plaza needed light sufficient to create a feeling of safety but not so bright that the lighting would compete with the 9/11 Memorial, which is internally lit. Similarly, the tower lobbies along Greenwich Street had to be lit in a way that would not create glare or other impediments to seeing the memorial. FMS developed the plaza lighting with landscape architect Peter Walker, co-designer of the 9/11 Memorial. Each lighting fixture, eight inches (20.3 cm) square, seems to disappear within the allées of trees, quietly fitting into the plaza. They cast a warm, horizontal light. “Our mandate was to light the people, not the floor. In other words, we’re really interested in what the people are doing, not what the ants are doing,” Marantz said of the horizontal beams.

Dozens of stores and restaurants animate the World Trade Center’s public spaces. Many, especially those showcased inside the Oculus, are upscale retailers such as Apple and Hugo Boss, but there are a few places where one can buy a toothbrush. Westfield developed the project’s retail component.

Cortlandt Way, a casualty of the Twin Towers’ construction in the 1960s, has been restored, designed by PWP Landscape Architects. Now reserved for pedestrians, the terraced walkway is a primary access route to the memorial. It is paved in Mesabi Black granite, which is also used on the plaza, but here the cobbles are much smaller, in keeping with the street’s intimate scale. Signage and lighting are similarly minimal and subdued.