Each Manhattan tourist map contains 100 plastic coated lenses per inch. Under each tiny lens lie three separate images containing geographic data. These data layers are sliced and stacked on top of one another making each slice just 1/300th of an inch wide. That’s small enough for the Dynamap to play subtle tricks on a viewer’s eye. The viewer thinks she sees multiple layers of information, almost like a hologram. Hold the map at one angle and New York’s subway system emerges. Hold it at another and the city’s neighborhoods appear. Hold it at a third angle and see the city’s street grid.