Municipium Cives Romanorum Felicitas Julia Olisipo (in Latin: Olisippo or Ulyssippo ; in Greek: Ὀλισσιπών, Olissipṓn, or Ὀλισσιπόνα, Olissipóna) was the ancient name of modern-day Lisbon while it was part of the Roman Empire.

During the Punic wars, after the defeat of Hannibal, the Romans decided to deprive Carthage of its most valuable possession, Hispania.

[6] Uncovered in 1771 following Lisbon's devastating earthquake, the true purpose of these underground Roman passages has been subject to varying interpretations.

Contemporary consensus leans towards them being a cryptoporticus—a structural innovation of the Roman Empire times, used to stabilize and level the ground for significant constructions, particularly in uneven terrains.

[6][8][9][10][11] Several temples were built in the city, dedicated to Jupiter, Concordia, Diana or Minerva (on the castle hill), Cybele (near current Largo da Madalena), Tethys (current São Nicolau church) and Idae Phrygiae (an uncommon cult from Asia Minor), to the Imperial Cult and to Vestal Virgins (in Chelas).

Economically, Olisipo was known for its garum, a sort of fish sauce highly prized by the elites of the Empire and exported in amphorae to Rome and other cities.

During this period, he organized the tribes of Lusitania (and Hispania) and was on the verge of forming an independent province in the Sertorian War when he died.

Petitions are recorded addressed to the governor of the province in Emerita and to Emperor Tiberius, such as one requesting help dealing with "sea monsters" allegedly responsible for shipwrecks.

[16] There is also the legend of Saint Ginés (São Gens), presented as one of the first martyr bishops of Lisbon and remembered in the Nossa Senhora do Monte chapel.

The territory includes the following Roman archaeological finds, known settlements or place names: Lisbon suffered invasions from the Sarmatian Alans and the Germanic Vandals, who controlled the region from 409 to 429.