An improved apparatus for providing access to the floors of a building during an emergency such as a fire, the apparatus including a structural support positioned on the exterior of a building and a transport system to transport persons or materials between the floors of the building along such support. The transport system includes a drive system for moving an elevator platform vertically along the support structure. An independent power source and the elevator platform are initially contained within a protective enclosure prior to their desired use. Other embodiments are also disclosed, including an adaption of the apparatus to buildings equipped with setbacks.