A catenary arch is a type of curve formed by a hanging chain or cable when supported at its ends. This shape is mathematically defined and represents the ideal form for structures that need to support weight evenly. The catenary curve is often seen in bridges and buildings, where it helps distribute loads efficiently. The term "catenary" comes from the Latin word "catena," meaning chain. Famous examples of catenary arches include the Gateway Arch in St. Louis and the Sagrada Família in Barcelona. These structures utilize the natural properties of the catenary to enhance stability and strength.