Mysterious dream: Up!

I dreamt that I was up last night
No, not awake, and not in flight,
I dreamt that I was up on high
On a rock; or in a building – not in the sky
I could see the view for miles around
The clouds, the sea, and most of the ground.
But where was I looking, and what did I see?
Sometimes, my dreams are a mystery to me.
When on the rock, I could see the river below
As it split in two to continue its flow
Around the rock and down to the sea
But how I got there is a mystery to me…
When in the building I was on the fifth floor
In a large room, but there wasn’t a door
It was an open plan office, that was as clear as day,
And in the far corner was an open stairway 
I looked through a window, but what did I see?
I don’t know; that’s another mystery to me…
Sometimes my dreams are crystal clear,
Sometimes my dreams leave a feeling of fear
Sometimes my dreams are random and fun,
And sometimes they’re forgotten before the day has begun.  
Parts of my dream are still in my mind,
But only the parts that I can still find.
When stood up on the rock I could see far and wide,
Yet when in the room I couldn’t see outside.
My dreams may have a meaning for me
But this one is a real mystery to me!