What Used To Be On This Empty Grand Junction Lot?

With all the activity surrounding the former Johnson's House of Flowers building, I noticed something in the lot behind it.

I am the first to admit that I know less than nothing about construction, building, plumbing, you name it. So, I have no idea what these things are. But, I don't feel too bad, I asked a couple other people and they didn't know either. Nor do they know what used to be on that back lot behind Johnson's.

What are these? Some are wood and some are concrete?

Is it simply an old foundation? But, it still makes me wonder what stood there and how long has this been an empty lot?

BONUS VIDEO: Grand Junction Ghost Video