Philippe II of Spain (1527-1598) ruled an empire that joined to the Spanish possesions the former portuguese empire (to later become again independent) and many other possesions in Europe; this empire touched all the continents on earth, and it is said that the sun never set on it.
In 1559 the king decided to erect a new monastery in El Escorial; what initially was to be a large religious center linked to the royal pantheon became the center of the royal power. The first books arrived in 1565, and in 1576 there were already 4546 volumes. In subsequent years, the library was subject to a fire and several threats. Today it is a tourism destination (if you visit El Escorial, it is right over the main gate). It is not a space to be compared to large modern libraries, but its riches are more in the quality and age of the volumes than in their sheer number.
The main hall is 54 meters long, 9 wide and 10 high, with a barrel vault over its entire length. It is an outstanding example of interior architecture from the Renaissance.