The Roman colony of Emerita Augusta was founded in 25 BC, possibly on a native foundation, by Augustus, to resettle emeriti soldiers discharged from the Roman army from the veteran legions of the Cantabrian Wars: Legio V Alaudae, Legio X Gemina, and possibly Legio XX Valeria Victrix. The city was the capital of the Roman province of Lusitania, and was one of the largest in Hispania with an area of over 20,000 square kilometres. It had three aquaducts and two fora.
The city was situated at the junction of several important routes. It sat near a crossing of the Guadiana river. Roman roads connected the city west to Felicitas Julia Olisippo, south to Hispalis, northwest to the gold mining area, and to Corduba and Toletum.
Today the Archaeological Ensemble of Mérida is one of the largest and most extensive archaeological sites in Spain and a UNESCO World Heritage Site since 1993.