In the Roman Empire, the city was known as "Emerita Augusta", the capital of the province of Lusitania. It was founded in 25 BC by Emperor Augustus as a colony for the veteran soldiers ("emeritus") of the Roman legions. The city was very important in Roman Hispania. It was endowed with all the comforts of a large Roman city and served as the capital of the Roman province of Lusitania. For centuries, until the fall of the Roman Empire, Mérida was an important economic, military, and cultural center. Following invasions from the Visigoths, Mérida remained an important city of the Visigothic Kingdom of Hispania in the 6th century. In 713, the Arabs conquered the city and devastated it. Even under Islamic rule, Mérida remained a bishop's seat until it was moved to Santiago de Compostela in 1119. In 1230 the Christian troops under Alfonso IX conquered Mérida during the Reconquista. The "Puente romano de Merida" is considered to be the longest bridge preserved from antiquity. In Roman times, the structure spanned the Guadiana River on 62 arches with a total length of 755 m. Today the bridge is 721 m long and rests on 60 arches. The bridge was constructed concurrently with the founding of the colony in the last decades of the 1st century BC. It was built on a shallow part of the river, where there is also a river island. Originally, two separate groups of arches spanned the river, connected by a wooden structure. However, parts of the original bridge were destroyed in a flood in 1603. It was then decided to connect the two groups of arches in the middle using additional arches. Since then, the bridge has run in one piece over the river. Until 1990, cars could cross the bridge.