The ACROPOLIS of Athens is an ancient citadel located on a rocky outcrop above the city of Athens. It is a UNESCO World Heritage Site and contains the remains of several ancient buildings, including the Parthenon. The Donat is a tower located within the ACROPOLIS, built in the 4th century BC. It was used as a watchtower and a place of refuge during times of war. The Coed is a wall that surrounds the ACROPOLIS and was built in the 5th century BC. It was designed to protect the citadel from invaders.