Designed by Daniel H. Burnham & Co. in 1902, the Flatiron Building is one of New York City’s most recognizable landmarks, officially recognized as such in 1966 by the Landmarks Preservation Commission. FPE Architects designed the building’s window replacement program, which required submission to and approval by this commission. Pre-design investigation revealed that the original windows, which were double hung in a single-glazed wood, were clad in copper with a patinated finish. FPE’s approved design specified new double-hung windows, in insulated glass and aluminum, with a custom-painted finish to match the original, patinated copper finish.