In the early 16th century, a huge defensive wall was built encircling the southwest end of Cádiz. The two bastions named San Roque and Santa Elena were designed to prevent attacks by land. This is now the demarcation between the historic center and the neighborhood of Puerta Tierra. In 1756, this magnificent marble Ground Gate was created in the curtainwall by Torcuato Cayón, a prolific and talented Spanish architect. About a century later, the Puerta de Tierra Tower was added as an optical telegraph station. When Puertas de Tierra (Gates of Earth) were extensively remodeled in 2013, a fountain and reflection pond were built as part of Plaza de la Constitucion.