 The widening alterations to Puerta del Sol in 1856 led to the Casa de Correos finally hosting the Ministry of the Interior.The preliminary draft was approved by the minister of Public Works, Claudio Moyano, for the expansion on 19 July 1860; following the proposal project of the architect and engineer Carlos María de Castro to expand the old city limits.During Spain's restoration period, the Paseo del Prado and Recoletos continued being the preferred location for prestigious institutions and organisations, as well as mansions.