About 45 minutes from Akchour (1.5km), a huge reddish-brown stone arch towers 25m above the river Oued Farda. Unbelievably, the bridge wasn't carved by human hand, but rather by the river's flow over countless millennia. As the river carved a path deeper and deeper, it left the bridge high and dry. To get here, go right at the Akchour dam and hug the steep mountainside all the way to the bridge. Alternatively, go down the canyon and follow along beside the river to look up at the bridge. The trip can be challenging either path you take. Don't try to descend to the water from where the bridge meets the mountain – loose rocks have been known to give way. Small cafes along the water and at the bridge sell tea and tajines.