The Royal Monastery El Escorail, or fully named "The Royal Site of San Lorenzo de El Escorial" is a massive historical residence of the King of Spain. It is situated in the town of San Lorenzo de El Escorail and it's quite close to Madrid, less then 50 km, so it receives a lot of visitors that are staying in Madrid, over 500,000 each year. It is also a declared as a UNESCO World Heritage Site. The construction of the monastery started in 1563 and lasted 21 years. Throughout history it had many functions, monastery, royal palace, basilica, pantheon, museum, library, university, etc...