The Autovía A-66 is a major highway in western Spain. It also forms part of the European Route E803. The road is an upgrade of the N-630 which is being undertaken section by section. The route roughly corresponds to the ancient Roman

Ancient Rome

Ancient Rome was a thriving civilization that grew on the Italian Peninsula as early as the 8th century BC. Located along the Mediterranean Sea and centered on the city of Rome, it expanded to one of the largest empires in the ancient world....

 'Silver Route

Via de la Plata

The Vía de La Plata or Ruta de la Plata is an ancient commercial and pilgrimage path that crosses the west of Spain from north to south, connecting Mérida to Astorga, and in extension Seville with the Bay of Biscay, at Gijón...

' from the mines of northern Spain to the Mediterranean.

It starts at Seville

Seville

Seville is the artistic, historic, cultural, and financial capital of southern Spain. It is the capital of the autonomous community of Andalusia and of the province of Seville. It is situated on the plain of the River Guadalquivir, with an average elevation of above sea level...

 with a junction with the Autovía A-49

Autovía A-49

The Autopista A-49 is a major highway in Andalusia, Spain. It connects Seville with the border of Portugal. It is also European route E1....

. It heads north through the wooded Sierra Morena

Sierra Morena

The Sierra Morena is one of the main systems of mountain ranges in Spain.It stretches for 400 kilometres East-West across southern Spain, forming the southern border of the Meseta Central plateau of the Iberian Peninsula, and providing the watershed between the valleys of the Guadiana to the...

and passes over the Puerto de las Marismas. It then crosses from Andalucia into Extremadura

Extremadura

Extremadura is an autonomous community of western Spain whose capital city is Mérida. Its component provinces are Cáceres and Badajoz. It is bordered by Portugal to the west...

. It heads through the town of Zafra

Zafra

Zafra is a town situated in the Province of Badajoz , and the capital of the comarca of Zafra - Río Bodión. It has a population of 16,242, according to the figures of 2009....

 on the way to Mérida

Mérida, Spain

Mérida is the capital of the autonomous community of Extremadura, western central Spain. It has a population of 57,127 . The Archaeological Ensemble of Mérida is a UNESCO World Heritage site since 1993.- Climate :...

 crossing the Tierra de Barros. It ends in a junction with the Autovía A-5

Autovía A-5

The Autovía A-5 is a Spanish autovía which starts in Madrid and ends in Badajoz. It is part of the European Road E90.- Sections :- Major cities crossed:*Madrid*Alcorcón*Móstoles*Navalcarnero...

.

North of Mérida the road crosses the Sierra de San Pedro to the town and world heritage site of Cáceres

Cáceres, Spain

Cáceres is the capital of the same name province, in the autonomous community of Extremadura, Spain. , its population was 91,131 inhabitants. The municipio has a land area of 1,750.33 km², and is the largest in geographical extension in Spain....

. Then the road crosses the Tajo and Almonte rivers. The road heads north east as it enters the Sierra de Gredos. The road becomes the N-630 (at km 489) south of the town of Plasencia

Plasencia

Plasencia is a walled market city in the province of Cáceres, Extremadura, Western Spain. , it had a population of 41,447.Situated on the bank of the Jerte River, Plasencia has a historic quarter that is a consequence of the city's strategic location along the Silver Route, or Ruta de la Plata...

. It then heads to the university town of Salamanca

Salamanca

Salamanca is a city in western Spain, in the community of Castile and León. Because it is known for its beautiful buildings and urban environment, the Old City was declared a UNESCO World Heritage Site in 1988. It is the most important university city in Spain and is known for its contributions to...

 via Béjar

Béjar

Béjar is a town and municipality in the province of Salamanca, western Spain, part of the autonomous community of Castile and León. It lies had a population of 15,016 .-History:...

. The road crosses the Rio Tormes and the Autovía A-62

Autovía A-62

The Autovía A-62 is a highway in Spain. It connects the Portuguese Border with Salamanca, Valladolid and Burgos. It is part of the European route E-80....

 before travelling north to Zamora

Zamora, Spain

Zamora is a city in Castile and León, Spain, the capital of the province of Zamora. It lies on a rocky hill in the northwest, near the frontier with Portugal and crossed by the Duero river, which is some 50 km downstream as it reaches the Portuguese frontier...

 and the Rio Duero. 18 km north the road meets the reservoir Embalse del Esla de Ricobayo, here the N631 heads north west to the Autovía A-52

Autovía A-52

The A-52 is a highway in western Spain. It starts at Vigo heads east from the town crossing the Autopista AP-9 and then the N-550/Autovía A-55. It then goes over the Rio Tea running parallel to the N-120 and along the Rio Miño. At Ourense the road turns south out of the valley in conjunction...

, and the N-630 along the Rio Esla to the Autovía A-6

Autovía A-6

The Autovía A-6 or Autopista AP-6 is a Spanish autovía and autopista route which starts in Madrid and ends in Arteixo ....

. 6 km north the A-66 branches to the north with a downgraded N-630 parallel. The road then enters the provence of León

León (province)

León is a province of northwestern Spain, in the northwestern part of the autonomous community of Castile and León.About one quarter of its population of 500,200 lives in the capital, León. The weather is cold and dry during the winter....

.

At León

León, Spain

León is the capital of the province of León in the autonomous community of Castile and León, situated in the northwest of Spain. Its city population of 136,985 makes it the largest municipality in the province, accounting for more than one quarter of the province's population...

 the road becomes a toll Autopista AP-66 and the N-630 a trunk road as they pass through the Montes de León and Sierra Cantábrica. South of León there is a junction with the Autopista AP-71

Autopista AP-71

The Autopista AP-71 is a highway in the province of Leon, Spain. It connects the cities of Astorga and Leon.It starts at a junction with the Autovía A-6 and heads north east parallel to the N-120 to Leon and the Autovía A-66 south west of the city....

 and Autovía A-231

Autovía A-231

The Autovía A-231 is a highway in Spain known as the Autovía del Camino de Santiago between Burgos and León.It is currently under construction and follows the route of the N-120 passing via Logroño and Burgos where it becomes the Autovía A-12....

. The N-630 crosses the Alto del Rabizo (1,160m) and Puerto de Pajares (1,379m). The AP-66 passes through the Túnel de Negrón. Entering Asturias

Asturias

The Principality of Asturias is an autonomous community of the Kingdom of Spain, coextensive with the former Kingdom of Asturias in the Middle Ages...

 the roads re-converge 36 km south of the next major city Oviedo

Oviedo

Oviedo is the capital city of the Principality of Asturias in northern Spain. It is also the name of the municipality that contains the city....

. There is a junction with the Autovía A-64

Autovía A-64

The Autovía A-64 is a highway in Spain. It connects the Autovía A-64 junction 367 km with Oviedo.It heads south east through the Tunnel Fabares, then meets the N-634 before heading west to Oviedo and ending at the Autovía A-66....

 and AS-1. The A-66 finally ends 13 km north of Oviedo at a junction with the Autovía A-8

Autovía A-8

The Autovía A-8 is a highway that connects all the regions on the Northern Coast of Spain. It is known as the Autovía del Cantábrico and connects Baamonde and Bilbao, where it continues as the Autopista AP-8 to the French border...

 near Gijón

Gijón

Gijón , officially Gijón / Xixón, is a coastal industrial city and a municipality in the autonomous community of Asturias in Spain. Early mediaeval texts mention it as "Gigia". It was an important regional Roman city, although the area has been settled since earliest history...

on the Atlantic Coast.