(from amusing planet)
Many of the seaports of the Mediterranean, particularly in its eastern end, that played such a large part in the history of Europe and the Middle East from 1000 BC until the 18th century, are now much diminished, and often forgotten relics. One of these is Monemvasia on its island, connected today only by a narrow causeway to the Greek mainland. In its 14th-17th century heyday it may have been home to as many as 40,000 inhabitants.
(from vacations to go)
The town was a latecomer as an historic port town. The island was only severed from the mainland by an earthquake in 375 AD and the town itself was not founded until the 6th century by refugees from the mainland seeking the protection the Byzantine Empire could not afford them, from the Slavic and Avar invaders of Greece.
(from huffington post)
By the 10th century it was a thriving port. In those days, the Mediterranean was dominated by galleys, which stuck near to the coast and needed to seek ports frequently to take on water, so itineraries tended to be between closely situation ports. With its location, Monemvasia was ideally suited as a stopping point for traffic between Venice, Genoa, Amalfi and other Italian seaports and Constantinople, Thessalonica and the harbors of Asia Minor.
Monemvasia's island provided protection and security. It is about 1 km long and 300 meters wide with a hill rising to about 500 feet. In those days, there was a lower town, which still exists, and an impregnable upper town (now abandoned).
(from amusing planet)
As the Byzantine Empire began its long decline in the 13th century, Monemvasia became part of the Despotate of Morea (the Peloponnese). With the fall of Constantinople in 1453 and of the Despotate in 1460, both to the Ottoman Turks, Monemvasia decided to seek protection by turning itself over the the great seafaring state of Venice. In 1540, Venice ceded Monemvasia to the Ottomans, before briefly taking it back between 1690 and 1715, when it returned to the Turks. In 1821, Monemvasia was the first town liberated in the Greek War of Independence.
Today, the town is a popular tourist destination. Here's a Rick Steeves video to prove it!