Overview: Concrete: It is the most widely used building material on earth. It was a building block of the Roman Empire and is a material of choice for a new generation of gravity-defying skyscrapers. From the sidewalks of New York to the fast-growing Burj Dubai, slated to be the worlds tallest building when it is completed in 2008, concrete continues to be a crucial tool of engineers and architects alike. Concrete's footprint is everywhere.