An ancient olive tree is beside Hagia Sophia Holy Orthodox Church in the upper town of Monemvasia, Greece.

A dome with 16 windows rises above 12th century Hagia Sophia Holy Orthodox Church in the upper town of Monemvasia, Greece.

Hagia Sophia Holy Orthodox Church (1150) in the now unoccupied upper town of Monemvasia, Greece, is only accessible via a steep zigzag pathway. During its 800-year history, it has served many different faiths including Catholic, Orthodox, and Muslim.

The tightly packed lower town of Monemvasia, Greece, with its terracotta roofs, clings to precipitous rocky slopes. The town was founded in the 6th century AD by Spartans fleeing various invaders.

Elkomenos Christos Greek Orthodox church (1691) stands on the main square of the lower town of Monemvasia, Greece.

The narrow cobbled streets of the lower town of Monemvasia, Greece, are sometimes covered with vaults over which sections of houses have been built.

A gate through the medieval walls of Monemvasia, Greece, gives access to one of the oldest continuously occupied fortress towns in Europe.

Known as the Gibraltar of Greece, the strategic fortress town of Monemvasia has been hotly contested by the Byzantines, Ottomans, Venetians, and many others over its 1,400-year history.

Monemvasia Island in southern Greece is a limestone monolith protruding from the Aegean Sea.

The rock island of Monemvasia, Greece, rises abruptly from the Aegean Sea. Since 1971 a single causeway has linked Monemvasia to the Peloponnese.