A weeklong, 1,000km ride from Seville to Salamanca along a 2000 year old dirt path used by Roman traders and medival pilgrims. Highlights of the route include swings by old castles and ruins of the Roman ampitheater at Merida. If you want a supported tour, a trip leaves annually after Semana Santa (Spainish Easter) which is the countries busiest travel week and is offered by Camino Tours.
Note: In Spain, mountain biking is known as Bici Todo Terrano (BTT) and the forest tracks open to BTT are known as pistas forestales.
Overall, La Ruta De La Plata is the 4th most popular mountain bike trail of all 20 mountain biking rides in Spain.