This probably is a waterfall sometimes. There is some water https://i.nostr.build/OoxuOdYSLcqEOi4K.jpg visible lower down.

Beside it and next to the tunnel exit, which continues into another tunnel, is the old goat track, carved into the side of the cliff and bolstered with a massive stone and mortar wall.

It must be hundreds of years old. 

https://i.nostr.build/fStQoPZgZboyWMDL.jpg