Is this a greenhouse base? What should I do with it (removing it is not an option)

I have this at the bottom left of my garden and I’m a bit torn on what to do with it. It’s a bit worse for wear I tried having my shed on it but it’s the sunniest spot in the garden so I moved it. I can’t get my garden done professionally so I can’t get it removed I wanted to get some opinions on what to do with it.

Option One: clean it up paint the base and use it as a planter

Option Two: spruce it up by pressure washing it clean, painting it with masonry paint and fill the middle with gravel. Use it as a relaxing reading area with a comfy chair maybe an arch going over it with a climber? I’m wondering if it’s too ambitious and it won’t look good anyway it’s cracked in places.

Option Three: get a cheapie greenhouse on it I’m not sure I will use since I’m not much of a gardener yet.

Any other ideas are welcomed and appreciated