There are several versions of this dream, so I have created a bit of a composite.
I stand on a viewing walkway. Stretching out below for many kilometers in front and to the left and right is the burning ruins of a city. Smoke still rises from some of the ruins, but no building stands. The highest standing walls are only a few feet high. A little trickle of a river flows trough the city. In the distance there are black mountains. But there is a hole and a little trickle of light. I fly down the hole. It is a vertical shaft well lit. There are shiny rungs and the light is a golden yellow. As I approach my existence is detected. There are people I know quite well down there. It is a control room of sorts. As I get closer the escape though a hatch to another existence. The room at the base is about 30 feet across. It is a circular control room. Now abandoned. The controls are futuristic computer panels.