The Spiral Staircase is a double helix. It is composed of two staircase which allows people to go up and down without crossing each other. This staircase is now intended only as the exit from the Vatican Museums. We took the metro three stops down to visit the Spanish Steps. This wide, curving staircase is one of Rome’s iconic sights. We were too tired to climb the steps, so we sat on the wall of a fountain and admired the piazza.