Land of Legends
Nivus is a seaside fortress from the Second Age. It had a dock below the cliff it is on and a carved runnel upwards into the fortress from there, but most of the fortress sat on top of the cliff. No one is exactly sure what happened to it, but at some point it was abandoned and it had fallen into serious disrepair before anyone thought of rebuilding it. It was briefly made livable again during the Third Age before being abandoned yet again.