Patios, structurally, are key as supporting loads of interior facades. The floor of the courtyard is supported by pillars of cast iron. In the courtyard, there are traditional elliptical beams and girders but Gaudí applied an ingenious solution of using two concentric cylindrical beams with stretched radial beams, like the spokes of a bicycle. They form a point outside of the beam to two points above and below, making the function of the central girder a keystone and working in tension and compression simultaneously. This supported structure is twelve feet in diameter and is considered "the soul of the building" with a clear resemblance to Gothic crypts. The centerpiece was built in a shipyard by Josep Maria Carandell who copied a steering wheel, interpreting Gaudí's intent as to represent the helm of the ship of life.