The Monastery of San Lorenzo de El Escorial is located about 50 kilometres northwest of Madrid. It was founded by Felipe II and built to commemorate the victory at the Battle of San Quintín. The work began in 1563 and was finished by 1584. Its location is said to be decided on the advice of astrologers, doctors, philosophers, quarrymen, theologians and architects.
El Escorial was built on the idea of maintaining symmetry and austerity, while also showing the power of the crown of Spain. It has many noteworthy sights, such as the servants' quarters, the Queen’s quarters, the Infante’s (or Upper) house, and the Prince’s (or Lower) house. If you have enough time in Madrid, consider El Escorial as a day trip.