The rock is probably in the Tribune Tower in downtown Chicago. Robert McCormick owner and builder of the tower placed selected stones on the lower 10 or so feet of the building from structures around the world.
The base of the building is studded with over 120 stones from famed sites and structures in all 50 states and dozens of foreign countries. They range from the Parthenon (Greece) and Taj Mahal (India) to Bunker Hill (Massachusetts), Mark Twain's "Injun Joe Cave" (Missouri), ALamo (Texas), Colosseum (Rome), Great Wall (China), and a moon rock!
His mansion at Cantigny (Wheaton,Illinois and home of the excellent 1st Division Museum) also has selected stones from famous world buildings. It was the early 20th century when the well-to-do did that sort of thing.
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