The castle of Rustrel
The castle, incomplete, only had three towers until 1992, when the fourth tower was finally built. If the town hall is open, you can go inside to admire the hall, with a monster's head as the key piece of the main archway, and a beautiful stone staircase.
Returning down from Rustrel, a road to the left, at the exit to the village, leads you to the wash house. A date is inscribed on it: 1738. The canal water in a mine supplies it, and its source never dries up. There again, there's a nice little cobblestone road. And there again, the orangey colour of the wall hints at the ochre from the Colorado.