200 Fifth Avenue in Manhattan. Ed Eckstein photo (right).



The 850,000-square-foot, 14-story commercial property, overlooking Madison Square Park in Manhattan’s historic Flatiron District, was restored and transformed to a premier Class A office building. This landmark building, constructed in 1909, is a steel-framed structure with concrete floor slabs, and masonry, terracotta and stone exterior walls.

Thornton Tomasetti provided structural engineering, historic façade restoration, exterior wall consulting for a new glass curtain wall, and façade engineering for the pre-stressed steel cable structural glass entrance. The structural alterations include widening of the existing courtyard at the lower floors creating new floors in the west portion of the courtyard from the second through the fourth floors, creating a dramatic three-story high lobby space. The elevator lobbies at the east end of the courtyard are extended for the entire height of the building. The lobbies are enclosed by a structurally glazed façade with terracotta louvers that overlook the courtyard, allowing the infiltration of abundant natural light.

The building features many sustainable design elements including light-filled vertical gardens in the courtyard that provide insulation, conserve energy and reduce storm water runoff. Many building materials and components also are locally manufactured and pre-assembled. This project received LEED Gold certification.

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