I would like to tell you that this water spillway leads to Narnia or Atlantis, but I would be calling off the search for the true portals. It’s purpose is less fantastical, but still very impressive. It is part of a hydroelectric dam in Portugal’s Covao do Conchos.
Built in 1955, this void moves water from ribeira das Naves to Lagoa Comprida. The tunnel is a staggering 1,519 meters long (4983.59 ft). People travel to this area specifically to see this man made wonder. The rate of water flow, the perfectly circular entrance and the build up of moss gives structure a wonderfully unnaturally natural appearance.
You can see this and other naturally beautiful scenes on the hiking trails throughout the Serra de Estrela mountains. This water spillway is one of the most artistic and utilitarian of man made structures.