Treatise of Architecture and Machinery of Juan de Herrera.
Conserved in the Archivo General de Simancas, Casa y Sitios Reales [Leg. 258, fol. 488 (15467-1577)].
The only autograph treatise by the architect who carried out the major portion of the Real Monasterio de El Escorial. It is centered on the motor principle of the pulleys that were employed in the construction of the monastery.
Accompanied by a scientific study volume of 122 pages by Luis Cervera Vera, doctor of architecture and member of the Real Academia de Bellas Artes de San Fernando.