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 'Silver Route' from the mines of northern Spain to the Mediterranean. The final section of road south of Benavente is under construction as of October 2013 with completion anticipated in 2015.RouteAutovía A-66 starts at Seville with a junction with the Autovía A-49. It heads north through the wooded Sierra Morena and passes over the Puerto de las Marismas. It then crosses from Andalucia into Extremadura. It heads through the town of Zafra on the way to Mérida crossing the Tierra de Barros. It ends in a junction with the Autovía A-5.North of Mérida the road crosses the Sierra de San Pedro to the town and world heritage site of Cáceres. 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. It then heads to the university town of Salamanca via Béjar. The road crosses the Rio Tormes and the Autovía A-62The section north of Zamora leading to the Rio Duero. 18 km north where the road will meet the reservoir Embalse del Esla de Ricobayo is under construction as of October 2013. Here the N631 heads north west to the Autovía A-52, and the N-630 along the Rio Esla to the Autovía A-6. 6 km north the A-66 branches to the north with a downgraded N-630 parallel. The road then enters the province of León.