You are right again Ramon: I think that this location is in Italy, near Rome and Elios Studios where was shot the first hanging of Tuco (the second was in El Paso set, the third in Higo Seco in Cabo de Gata, near Albaricoques and Fernan Perez, u know) but I have not the proof: too much "dineros" are wanted to make trips over the world to search Leone locations!!!

Another very important location is White Rocks set: prof. Frayling says that is the El Paso set but I don't agree.
Maybe White Rocks was shot partly in Italy partly in Spain: when il Monco arrives in the rainstorm was shot in Spain (Colmenar?), when he goes away was shot in Italy, maybe near the location asked in this topic.
An intriguing possibility!
Best
AS