NEW YORK CITY-Construction on the 26-acre Hudson Yards development on Manhattan’s Far West Side formally launched Tuesday morning with a groundbreaking for what will be the south tower—a 47-story office tower that will serve as the new headquarters of Coach Inc. Tuesday’s ceremony, which culminated in the drilling of caissons that will anchor the tower, comes after the Metropolitan Transportation Authority’s board approved an amended contract with the Related Cos. that commits the developer to close on its 99-year ground lease by June 1, 2013.

Noting that the city’s history has been defined by moments in which the seemingly unachievable—such as the Empire State Building and the Pennsylvania Railroad’s trans-Hudson tunnels—was conceived and brought to fruition, Related Cos. chairman Stephen Ross commented, “Today is our moment, our position in history. Today we formally begin construction of one of the most ambitious projects in history.”

From an engineering standpoint, the 1.7-million-square-foot tower to be anchored by Coach—and for which Ross said he has term sheets from two other tenants, making the property 80% committed before shovels go into the ground—will be the easy part. Much of the development will occur atop platforms that must be built over the MTA’s West Side rail yards, which are in active use daily. In all, the project will encompass 13 million square feet of development, including six million square feet of commercial space.

In order to create what Ross said will become “the new heart of New York,” more than the agreement between the MTA and development partners Related and Oxford Properties Group was necessary. Ross charted the public-private partnership that made Hudson Yards feasible, encompassing everything from the 2005 rezoning of the Far West Side to the creation of the High Line elevated park near the site and the MTA’s creative financing to extend the No. 7 subway line westward from its current terminus near Times Square. For these and he other efforts, he gave full credit to Mayor Michael Bloomberg, who in turn gave kudos to former deputy mayor for economic development Daniel Doctoroff as well as City Council Speaker Christine Quinn.

Joseph Lhota, the MTA’s executive director, recalled that as the city’s commissioner of finance in 1995, he noted that the Far West Side generated virtually no revenue for municipal coffers. On Tuesday, as head of the agency that owns the land on which Hudson Yards will be built, he noted that the project would do more than satisfy his “narrow” concerns of 17 years ago. “It’s going to be something you rarely see in New York—the creation of a new neighborhood.”

Also on hand at Tuesday’s ceremony were Manhattan Borough President Scott Stringer; Gary LaBarbera, president of the Building and Construction Trades Council of Greater New York; Robert K. Steel, who currently serves in the capacity once filled by Doctoroff; Ann Weisbrod, president of the Hudson Yards Development Corp.; and Lew Frankfort, Coach’s chairman and CEO.