The New York Times calls it “the biggest skyscraper New Yorkers have never heard of.” But earlier today, Silverstein Properties hoisted the final steel beam for its 977-foot, LEED Gold-hopeful 4 World Trade Center, topping out the understated – yet graceful – 72-story tower even while most eyes have been trained diligently on its more famous neighbor.

4 World Trade Center – located at 150 Greenwich Street – stands at the southest corner of the 16-acre World Trade Center site and was designed by the Pritzker Prize-winning architect Fumihiko Maki. Upon completion, the 2.3 million-square-foot 4 World Trade Center will be the new home of the Port Authority of New York and New Jersey, which signed a 30-year, 600,000-square-foot lease with Silverstein Properties (at $59 per square foot) back in 2008. That deal was made (loosely) in connection with the agreement where the parties swapped overall World Trade Center redevelopment rights with those for 1 World Trade Center.

Already the modesty of the tower’s architecture when compared with 2 World Trade Center (Norman Foster) and 3 World Trade Center (Richard Rogers) is winning Mr. Maki acclaim: the design aims to serve respectfully as a backdrop to the National September 11 Memorial. When it’s completed next year, the tower will at least temporarily be the second tallest at the World Trade Center site until construction continues on towers 2 and 3.

Office space at 4 World Trade Center will exist in two distinct floor plates. Low- and mid-rise floors (7 through 46) will feature 44,000-square-foot spaces in a parallelogram shape that mirrors the tower’s site plan. The high-rise floors (48 through 63) will be in the shape of a trapezoid of 34,000 square feet, triangulated from the lower floors to face 1 World Trade Center. Each configuration features a 45-foot span on the building’s west facade that faces over the 9/11 Memorial and is served by two elevator banks.