Peloponnesus, also known as Peloponnese, is a peninsula located in southern Greece, connected to the central part of the country by the Isthmus of Corinth. It is divided into several regions, including Corinthia, Laconia, and Messenia. It was the centerpiece of the civilizations of classical Greece, with cities such as Sparta, Corinth, and Mycenae, and later was the heartland of the Byzantine Empire and the first independent Greek state in modern times. The peninsula covers an area of about 21,500 square kilometers and is characterized by mountains and valleys.