My very resourceful sister bought a house with this old swingset frame in the backyard. When she wanted to add a bed for more veggies, she made a lasagna garden under the frame, and used the frame and some PVC pipe for trellises. As the plants got bigger, the PVC pipe was raised, and eventually it was all the way at the top.
To quote my sis, "It was a whole lot easier to leave the darn thing as it’s well-anchored in concrete, and just layer newspapers and soil on top of the grass inside the pavers salvaged from another part of the yard. Recycle!"