Fish-salting tanks (cetariae) at the Roman ruins of Troia · Wikimedia Commons (CC BY-SA)

Troia Fish Salting Factories

Cetobriga

Garum FactoryLusitania · Troia Peninsula, Setubal District, PortugalBuilt 1 CE · Destroyed 500 CE

About

Twenty-five separate workshops packed the Troia peninsula with 182 salting tanks between them, an industrial concentration UNESCO calls unmatched anywhere else in the Roman world. The workshops varied hugely in scale: the largest topped 1,000 square meters and held 19 tanks on its own, while the smallest ran to just 135 square meters and nine tanks. Tuna and sardines came out of the Sado estuary and went into amphorae as garum bound for the length of the empire. Production here ran continuously from the 1st century into the 6th.

What happened here

Rows of stone vats sunk into the ground beside the sea, and the smell reaches a long way inland. Small fish and the guts of larger ones are layered with salt and left in the sun for weeks; the liquid that separates off is drawn away as fish sauce and the residue is sold cheaply as paste. Grades run from a luxury sauce that costs more than good wine down to the version bought by everyone else. Tunny is netted in season from lookout towers on the headland, and the fishing, salting, potting and shipping all happen within a few hundred metres. Amphorae are stamped with the maker's name. Towns built on this are rich, and they are built downwind of themselves.

In ancient writing

Ptolemy, Geography 2.5
Lists Caetobrix among the coastal towns of Lusitania south of the Tagus, the ancient name conventionally identified with the fish-salting settlement on the Troia peninsula opposite Cetobriga.