Only 30 mi from Madrid, at the very heart of the Sierra de Guadarrama, lies San Lorenzo d'El Escorial. The town boasts fantastic architectural heritage with San Lorenzo d'El Escorial monastery, which was built under Philip II in the Renaissance style. It is a monumental work of art, and was considered for some time as the eighth marvel of the world for its size and symbology. It contains a vast collection of ancient tapestries, sculptures and sacred art, and in 1984, it was listed as a world heritage site by UNESCO. Visitors can admire some of the king's belongings, the crypt, the basilica and the library. It took 21 years to build (1563 - 1584), hence the Spanish saying "durar más que las obras de El Escorial" (literally, 'taking longer than the construction of El Escorial'), used to refer to something for which there seems to be no end in sight.
The second most visited monument is the Valle de los Caídos (some 5 mi from the historical centre), where are buried the dictator Fransisco Franco and 33,800 men who died fighting in the Civil War.