Still thinking about the giant hole behind the house

This is something way, way in the future, but I think about it often as it is going to be right in our face every time we go out the back door.

Here are a couple of pictures of what I think the deck should look like

The internet is a blessing and a curse...so many beautiful inspirations....so much time wasted looking for them...lol

Aloha a Hui hou!

What should we do with the hole?

The previous owners had planned on building a 2nd house right behind the main house. They had the foundation ready and it looks like the plumbing is there for it too. But for what ever reason, they never got around to putting it up. 

So now we have this HUGE 40'x60' foundation and are unsure what to do with it. We've been told that some critters have made their home under the boards and I don't want to encourage racoons, skunks, wasps or the likes to hang around that close to the house.

Part of me just wants to knock it down, fill it with soil and put up (or is it in?) some kind of deck/patio/lanai. Then again, leaving it as deep as it is gives us some other cool options. We could put in a sunken outdoor living room that would protect us from the wind...an outdoor fireplace, bread oven, outdoor kitchen, little pool....perhaps sell a kidney while I'm at it...lol

So here is the "hole":

The window to the right is a kitchen window and the window on the left is in the wood bedroom

Here is another view from the back corner

This view is from the irrigation pump - See how big it is? More that 2x's bigger than the entire house.

Here in the left part of the photo. The yellow ribbon runs around the edge of the foundation.

I'm a planner and a dreamer....The proportions are all off...but this would be kinda cool..

One can dream....

So, what would you do with it???