The Burj Al Arab in Dubai is an architectural marvel primarily constructed from steel, concrete, and glass, but it is its unique "skin" that makes it iconic. The building's structure is a steel "exoskeleton" that supports a massive concrete core. The most distinctive feature, the sail-shaped facade, is made of a double-layered, Teflon-coated fiberglass fabric (PTFE). This material was chosen because it can withstand the extreme desert heat and sandstorms while allowing a soft, translucent light to filter into the atrium during the day; at night, it serves as a giant projection screen for light shows. Inside, the hotel is a display of extreme opulence. It contains approximately 1,790 square meters of 24-carat gold leaf, used to decorate the elevators, pillars, and grand staircases. The floors and walls are clad in over 30 different types of Statutario marble from Italy and Brazil—the same marble used by Michelangelo for his sculptures. Furthermore, the hotel sits on an artificial island held in place by 250 concrete foundation piles driven 45 meters into the seabed, making the engineering of the "foundation" just as complex as the precious materials used in its interior.