Blockage

Now, I think I have run out of ideas. Poem making time? 

Once in lonely valleys lie,

A tower that could reach the sky. 

Towering high above the land, 

above the reach of human hand.

And within it's lonely walls it held,

a treasure that none could 

...I'm lost for a good word, and I feel lazy. I just can't think beyond that, and I feel pressured. :b