He used the equilibrium rule of the catenary, creating a spatial model of a building and testing the forces of gravity on it. He tested the strength of different materials, such as basalt and granite and experimented with lighting - for a better effect, he used mirrors or photographs to design. To decorate surfaces, Gaudi used the Catalan style of trencadis mosaic. His most mature works come from this period: Colonia Guell, Casa Mila or Sagrada Familia.
