Short answers, pulled from the story.
Juan de Herrera (1530-1597) was a Spanish architect, mathematician, and geometrician. He is best known for directing the construction of the Monastery of San Lorenzo de El Escorial and for developing the austere Herrerian architectural style that defined the Spanish Empire under Philip II.
The Herrerian style is named after Juan de Herrera and is characterized by bare granite surfaces, unified horizontal composition, and the deliberate omission of classical ornamental orders. It was representative of the architecture of the Spanish Empire under Philip II and his Austrian successors, and influenced Spanish architecture for over a century.
After becoming director architect in 1567 following the death of Juan Bautista de Toledo, Herrera enlarged the plan, built the monumental western facade, raised the central Basilica, and designed the pavilion of the Patio de los Evangelistas. He also modified the construction techniques and roofing, and changed the style of the facades to reflect his sober aesthetic.
Herrera designed the Cathedral of Valladolid, the Lonja de Sevilla (now the Archivo General de Indias), the Puente de Segovia in Madrid (1582-1584), and the original layout for the Plaza Mayor in Madrid. He also worked on the South Facade of the Alcázar de Toledo and the Puerta de Triana in Seville.
Juan de Herrera started his architectural career in 1561 with the Royal Palace of Aranjuez. In 1562 he contributed drawings to the Libro del saber de astronomía, and in 1563 he began working under Juan Bautista de Toledo on El Escorial.
As instructed in his 1584 will, Herrera's sepulchre was transferred after his death from Madrid to the Church of San Juan Bautista in Maliaño, Cantabria. He died on the 15th of January 1597.