The Acropolis is the most important ancient archaeological site in Greece and in the western world. It stands guarding Athens and is visible from almost everywhere within the city. The Acropolis Hill is also called as the “Scared Rock” of Athens. It is considered as the symbol of the city of Athens representing climax of artistic development in the 5th century BC. The Acropolis became the World Heritage Site in 1987. The most important monuments here include the Parthenon, built by Ictinus, the Erechtheon, the Propylaea, the monumental entrance to the Acropolis, designed by Mnesicles and the small temple Athena Nike.