A catenary arch is a type of arch that takes the shape of a hanging chain or cable when it is inverted. This curve, known as a catenary curve, is formed by the force of gravity acting on a flexible chain suspended between two points. Catenary arches are efficient structures, distributing weight evenly and providing stability, making them ideal for bridges and buildings. One famous example of a catenary arch is the Gateway Arch in St. Louis, which stands as a monument to westward expansion in the United States. The design of catenary arches has influenced various architectural styles, showcasing their strength and aesthetic appeal in structures like cathedrals and bridges.