There is no denying that One World Trade Center (WTC), the 104-story tower now rising at the northern end of the Ground Zero site, is a tremendously ambitious commercial real estate venture. The building, owned by the Port Authority of New York and New Jersey with the developer Durst Organization holding a 10 percent stake, will contain 3.1 million square feet of office space when completed in late 2013. Below grade, connected to the WTC site’s vast underground transportation infrastructure, there will be 55,000 square feet of retail, and near the top, the tower will include a two-level observation deck and a restaurant. But when the designers of the $3.19 billion project describe the building, they generally focus first on its potential as a symbol: “It will serve as the marker of the 9/11 memorial on the skyline,” says David Childs, consulting design partner to Skidmore, Owings & Merrill (SOM).