To the east of the promontory, at the mouth of the River Testene, there is a natural sheltered bay, called "Foce" in ancient times, but which is now almost completely silted up.

Then, in the 6th century, during the Greco-Gothic war (535-553), the Byzantines needed a secure, well-protected harbour, south of Salerno, so they fortified it, and called it Acropolis, meaning 'high town' or citadel.

This vast area constituted the feudal district of Agropoli which had been ceded to the bishops of Capaccio in Norman times and, except for brief periods, was possessed by them until the early decades of the 15th century.

In fact, in 1412, Pope Gregory XII ceded the feudal territories of Agropoli and Castellabate to King Ladislas of Durazzo (1386–1414) in partial payment of some war debts.

However, the Crown did not formally take possession until 1443, and before this, on 20 July 1436, King Alfonso V of Naples granted the fiefs of Agropoli and Castellabate to Giovanni Sanseverino, Count of Marsico and Baron of Cilento, requiring him to pay the Bishop of Capaccio 12 ounces of gold annually.

Apart from a few changes, such as the temporary transfer to Rodrigo d'Avalos, Marquis of Vasto, from 1505 to 1507, Agropoli and its feudal lands were held by the Sanseverino family until 1552, when Prince Ferrante was accused of treason, and forced to give up all his possessions.

It includes the hamlets (frazioni) of Frascinelle, Fuonti, Marotta, Mattine, Moio, Muoio, Madonna del Carmine, San Marco, Tarullo and Trentova.

To the west of the modern tourist harbour is another small promontory, on which the coastal tower of San Francesco (16th century) stands next to the much altered remains of the convent of the same name.