The history of the town of Alcobaça and its modern-day existence are indissociably linked to the almost seven century-long presence of the Cistercian Order in the town. The Order built one of the largest Cistercian monasteries in the world here at the confluence of the rivers Alcoa and Baça, after being granted a site by King Afonso Henriques.
Nevertheless, the origins of Alcobaça date back to the Roman period. The name the ancient settlement being Helcobatie.
Later the settlement took on the Arabic name of Al-cobaxa, made up of the article al and the word cobaxa meaning rams, which were a common feature on the hilly landscape around the town. The article al is common to both the name of the town and the names of many parishes in the municipality, such as Alfeizerão, Aljubarrota and Alpedriz.