Although concrete is the material most often used for home construction throughout the world, home buyers in the United States favor wood because it has been so readily available. But that's beginning to change. Concrete is gaining market share in the residential marketplace. Though the occasional concrete homes have been built for many years (including perhaps the world's most famous home, Fallingwater, designed by Frank Lloyd Wright), the driving forces behind the current level of interest are insulated concrete forms (ICF) and specialized removable forming systems. These newer methods for building concrete homes make them affordable and competitive with wood systems.