The use of the suspended chain.
Here, the 'catenaria' or suspended chain is used for the first time. The ends of a chain are fixed and the rest is left hanging, thus showing the ellipse formed due to the law of gravity, it is later surrounded with bricks.
It is worth mentioning the wrought iron dragon and the door which has a Celtic cross. The catenaria is used as an architectonic element. This is Gaudí's third work using bricks. It possesses several brick arches finished off with pinnacles. It is currently the site of the 'Catedra Gaudí de l'Escola d'Arquitectura de la Universitat Politècnica de Catalunya' (Polytechnic University of Catalonia Architectural School).