From the Archaeological Ensemble of Mérida World Heritage inscription:
The Archaeological Ensemble of Mérida, located in Extremadura, Spain, has its origins in the year 25 BC when Augustus completed the conquest of the North of Hispania and founded the Colony of Augusta Emerita. The city was created as an idealized model of Rome and was the capital of Lusitania, the western-most province of the Roman Empire. Following Diocletian’s reform, it functioned as the capital of the Diocese of Hispania. It was also temporarily the royal seat of two Germanic peoples – the Suebi and the Visigoths – and under the Arabic dominion, Mérida was one of the three border capitals of Al-Andalus, together with Toledo and Zaragoza, ensuring control of the western part of the Iberian peninsula.
The modern city of Mérida has been built on top of Emerita; yet, archaeological remains are well preserved and still evidence the Roman city. The 22 component parts of the property comprise an area of 31 ha. These include buildings for entertainment (theatre and amphitheater), the public architecture of the Forum and other spaces of power (provincial forum), engineering works (bridges, the dike, cutwater and clean and wastewater systems), and religious buildings, such as the Temple of Diana or the Temple of Marte. The property also includes excellent examples of private architecture, such as the Casa del Anfiteatro, La Casa Basílica, or Casa del Mitreo, which represent daily life. Most of the elements are located within the walled area of the Roman colony, but some are found outside its walls, such as the dams, aqueducts or thermal baths of Alange, in a natural environment and a landscape that has remained comparable to one of Roman times.
Mérida is a city in the Extremadura region of Spain with a population of 60,000. The city was originally founded as a Roman colony and it is best known of its Roman ruins.
The Roman ruins in the city are probably the best in the entire Iberian peninsula and among the best in the world. In addition to the signature Roman theater (see above), there is also a well-preserved aqueduct, one of the longest Roman bridges in the world, an amphitheater, arches, and a circus. The museum of Roman artifacts is one of the best museums of its kind that I have ever seen in the world.
Mérida should easily be on any list of top places in the world to visit to see Roman ruins and artifacts.