This is demonstrated in the exhibition's giant model of a CityHallTower for Philadelphia that was never built, a dramatic double helix derived from the discovery of DNA in 1953.
At New York by Geary, the 76-story tower on Spruce Street a few blocks from CityHall, 80% of the building is now taken, said Danny Charles, a spokesman for Citi Habitats, which is renting it out.