Many of famed architect Louis Kahn’s works have an air of mystery about them, but his design for the FDR Four Freedoms Park may be the most enigmatic of all. Built four decades after his death in 1974, the posthumous memorial to Franklin D. Roosevelt and his policies has today become one of the architect’s, and NYC’s, most popular urban spaces. While the memorial has been met with plenty of accolades for its seamless fusion of FDR’s core beliefs and Kahn’s signature style, its main inspiration is still unclear: Is it modeled after a boat’s prow referencing FDR’s love of the sea? Or is the shape speaking to something deeper? Recently unveiled sketches reveal that the design may have been influenced heavily by the masonic pyramid found on the back of the U.S. dollar bill.