The Greek name is usually read as Kallipolis , the beautiful city. The defensive site came first: the castle stands on foundations attributed to the Romans, damaged by Goths and then Vandals in the fifth century, rebuilt by the Byzantines , and held by the Normans shortly after the year 1000. Its first monumental fabric is Swabian ; the definitive construction is Angevin , around 1300, and the design has been associated with the military architect Francesco di Giorgio Martini . Originally quadrangular, it was given a polygonal enceinte with cylindrical corner towers under the Aragonese.

It housed serious company: Conradin of Swabia ; Queen Joanna II of Naples in 1414; Ferdinand I in 1463. Some historians hold that the painter Giuseppe Ribera , lo Spagnoletto , was born within its walls.

Gallipoli enjoyed a particular relationship with the Aragonese crown, from which it obtained favours and fiscal franchises . That ended abruptly in May 1484 , when — in consequence of the war over Ferrara — the Republic of Venice besieged and took the city in a memorable action in which the Venetian admiral Giacomo Marcello was killed. The Aragonese afterward strengthened the fortress further, adding the Rivellino , and ringed the coast with watchtowers, bastions and bulwarks. For centuries the castellano , the officer commanding the place, was a figure of standing in the civic administration — and, like most of the bishops, always of Spanish origin.

Then came the oil. The olives of the Capo di Leuca produced an olio lampante that was amber, transparent and burned with a brighter and cleaner flame — crucially, without smoke — which made it the best lamp oil in the Mediterranean. Through the whole seventeenth century Gallipoli was the leading European market for it. Ships left the port for Genoa, Naples and Venice , and from there the cargo reached France, Holland and England, and further to America, Russia and the Middle East. The oil lit the street lamps of the great capitals, and it was also used in wool-working and soap-making . The London exchange set its price against Gallipoli's quotations.

The frantoi ipogei are what that trade left underground. At least thirty-five of them are cut into the rock beneath the old town, many adapted from Messapian caves. Olives were milled below ground deliberately: the constant temperature of about seventeen degrees stopped the fruit spoiling. Only the mill beneath Palazzo Granafei — Renaissance in origin, named for its nineteenth-century owners — has been fully restored, and it keeps its presses and a seventeenth-century millstone.

The wealth is visible above ground too. The Cattedrale di Sant'Agata , in Lecce Baroque, was begun in 1629 . The Chiesa della Madonna della Purità , richly frescoed and fronted with three majolica panels, was built by the confraternity of the port dockers at the bay from which the oil ships sailed; it holds eighteenth-century paintings including work attributed to Luca Giordano . The Fontana greca stands at the entrance to the borgo, and in the eighteenth century the annual fair of Santa Maria del Canneto ran for eight days in the space before it, in the first week of July.

The town also built institutions. The Museo Emanuele Barba began in 1823 , when Carmine Fontò gave his books to the city; further donations came from the convents, and the naturalist Emanuele Barba later founded a zoological cabinet within it. The communal library , with its book collections and the historic archive , is housed in the thirteenth-century palace that held the nobles' oratory.