I've mapped, with the help of Landsat, the old Ruta de la Plata (Silver Route) from Benavente through Zamora to Salamanca.
We need to get Google to help us with their imaging. They're the only ones with decent aerial images of rural Spain.
In order to see this, you'll have to use the Osmarender layer. I've also asked for an account in order to help with the tiles@home project.