The market is completely different from post and pre 9/11, Silverstein remembers. "The progress is nothing short of compelling, it's remarkable," he said. "You look at the buildings that were here several decades ago, and the buildings that are here today, it's another city, it is a totally different environment, it is another community." 

According to Silverstein, the density of the buildings has grown vast and they are much taller and larger. Still reminders of what the market was are Landmark buildings permeating Lower Manhattan to a degree far greater than any other part of the city because they were the landmarks from the earliest days of New York City. "There are some of the architectural legends of federal landmarks of yesteryear," he said. "Going back to buildings built in 1915, 1918 and 1920," he said. "They're magnificent landmark buildings."

Neighborhoods have broadened Downtown Manhattan by virtue of landfills, such as in Battery Park City and over to the East River. The population in the neighborhood has also grown substantially, with more people than ever residing in the area than ever before. Office buildings have been converted into residential buildings, Silverstein said. "You see how the change has taken place in Lower Manhattan and today with 11 mass transit lines serving Downtown, it is the largest live-work-play population in the U.S.," he said. "It has the highest concentration of people living in communities in which they work. It's a complete change in which resonates the greatest." 

In a new book titled "A Century Downtown," highlighting the varied history of Lower Manhattan, Silverstein notes how the area has changed into a hub for tech and creative-focused companies. In the book's forward, he says, "this isn't your grandfather's Wall Street."