The Romans arrived at this region in 138 BC and settled in the city, then going by the name of Scallabis, and limited to the fortified area currently known as Alcáçova de Santarém.
A latter designation was "Scallabis Praesidium Iulium", given by Julius Caesar in 61 BC, with the installation of a military camp next to the previous fortifications. Most of the citizens were then inscribed in the Sergian Roman gens.
The city became one of the most important administrative centers of the Lusitania province in the 1st century AD, as head of a Conventus iuridicus, the Conventus Scallabitanus that included cities such as Olisipo, Seilium and Conímbriga. It was connected by important roads to Olisipo, Bracara Augusta and was the location of a Tagus river crossing.
Archaeological work in the Alcáçova de Santarém area has identified a Roman temple with a podium of about 15 by 15 meters, and part of the cella, dating from the 1st century BC (probably a Capitolium).Coordinates:  A theatre and baths from that period were also identified.
- "CРmara Municipal de Santarжm - Histзria e Geografia". Ribatejo.com. Retrieved 2011-10-28.
- "Santarem (Portugal) - Britannica Online Encyclopedia". Britannica.com. Retrieved 2011-10-28.
- "Monumentos". Monumentos.pt. Retrieved 2011-10-28.