When visiting Madrid, a trip to San Lorenzo de El Escorial should definitely be part of the plan. El Escorial is a massive monastery with the capacity of about 4000 rooms, which was built as a historical residence of the King of Spain. It now functions as a museum, a royal palace, and a school. The building is one of the most important ones of the Spanish Renaissance. It is also home to many paintings of local artists who lived in Spain, such as El Greco de Toledo.
Besides the impressive monastery, the area around it is full of beautiful nature, offering many opportunities to enjoy oneself outside the city.