The city is located on a hill at an altitude of 358 metres at the confluence of the Ebro and Cidacos rivers, and has an area of 91,41 km2. Calahorra is the second-largest city in La Rioja in population and importance, after the capital, Logroño. Its population is 21,060 people.
It is well connected to other cities, especially by highway. It is situated in the Ebro valley, 48 kilometres fron Logroño, 120 km from Zaragoza and 180 km from Bilbao, and is connected to these cities by national highway 232, the A-68 motorway (Vasco-Aragonesa) and the Bilbao-Zaragoza rail line.
Its daily bus services link it to such cities as Pamplona, Soria, and San Sebastián.
Its status as seat of a comarca and judicial district make it a service-industry city, in administrative, commercial, and leisure fields.
Calahorra has been inhabited since the Paleolithic, and its stable population dates to the Iron Age.
Rome conquered Calahorra in 187 BC and brought it to its highest point of importance as an administrative centre for surrounding regions.
Julius Caesar and Augustus Caesar gave the city (then named Calagurris) numerous distinctions, converted it into a municipality, and developed its city planning, economy, and politics. Its archeological remains show that it had a circus, baths, an amphitheatre, and other services found in large cities. It minted money and served as a justice administration centre.
Quintilian, well known for his descriptions of the culture of that time, was born in Calahorra, and the Parador in the city is named for him It has Roman ruins in the grounds.
Calahorra has since lost most much of its cultural weight to Arnedo.