I now walk past St. Patrick’s Cathedral every day on my way to and from Grand Central. Knowing that not that much in Manhattan is terribly old – like, say, Notre Dame (work on St. Pat’s began in 1858) – I wondered whether the great stone buttresses on the outside walls were structural in nature (necessary to keep heavy stone walls from collapsing) or merely ornamental, with the building itself upheld by a timber or iron frame. Anyone?