The stairs were originally known as the Boulevard steps, the Giant Staircase, or the Richelieu steps. The top step is 12.5 meters (41 feet) wide, and the lowest step is 21.7 meters (70.8 feet) wide. The staircase extends for 142 meters, but it gives the illusion of greater length. Due to the sightline, a person looking down the stairs sees only the treads, and the risers are invisible; whereas a person looking up sees only risers, and the treads are invisible.