Are the tree and the creek on your property?..what a shame not to capitalize on this feature...perhaps a picture that shows the whole area will lead to ideas...evidently whoever designed the house saw no potential in this feature as there are no windows facing it..this is just the sort of thing that handled properly can be a show stopper and add enough curb appeal to greatly increase your property value...whatever you do ...adding some vines or Rosemary to drape over the rock wall would help that feature to feel more like it is a natural part of the land..if you see any of this potential....a consult with an arborist may offer ideas to be sure the tree survives and thrives ...and also offer ideas for low maintenance landscaping appropriate for your area...if you have children ....this tree and space has tremendous potential for a play area...the stuff that memories are made of ...