This full-floor penthouse is located within the former attic of one of New York’s early skyscrapers, the Liberty Tower. Built at 55 Liberty Street in 1909 by Chicago architect Henry Ives Cobb, the Gothic Revival-style office building was the tallest in the world when completed. It was home to FDR’s law offices and, later, to German spies plotting to prevent American from joining WWI. Architect Joseph Pell Lombardi converted the tower to co-ops in 1979, with the attic unit retaining vaulted ceilings, exposed beams, and 29 windows offering views across the city. It’s now listed for $2.695 million.