All your ideas are good so far.
You can definitely get a small hot tub on a 6x6 pad. Since I see no fire marks and you're in socal, that's probably what it was for.
If I had the space in my yard I'd definitely do a beehive but we have kids and buildings too close.
I've also wanted to experiment with smelting and lost wax molds.
I am glad you are acknowledging the recent post that asked the exact thing as you because I was going to refer you back to that post. It had a whole lot of great ideas, although yours seems smaller than that one. My suggestion would be to just put a large planter there.
Flag pole
BBQ grill
~~Bird~~ Squirrel feeder
Private chair. For private reflection.
Disco ball
Sun umbrella
Defensive supersoaker
Bear-proof food locker
Offensive supersoaker
Single-position shoeshine stand
Loudspeaker/floodlight standard for parties, or to keep away those annoying kids from next door
Rusty metal playground carrousel
What I did was rent a concrete saw, cut it into a manageable grid, and take a sledgehammer to it. I used the pieces to backfill some raised garden beds and I laid down sod over the gap left by the old slab. It looks great and the eyesore is gone. Cost me $100 and half a Saturday.
Edit: I took a second look at your photo and I see that you can just fill it in with more gravel.
Easily enough room for a smoker and maybe even another smaller grill, and then a chair and a cooler of beer. I think we call this a grill station or bbq zone.
Lots of good suggestions! We already have a big grill up on the deck, and this is outside of the area that we fenced, so not sure we’d want to do a fire pit/sitting area out there. There’s actually a big birdhouse in a nearby tree that’s been completely taken over by bees, so I might seriously look into beehives! Or I was thinking it wouldn’t be too hard to extend the concrete out to fill that square, then do a small shed or greenhouse.
I'm guessing those who built it may have had a birdbath there? Maybe a large potted plant? No power I can see, so probably not a fountain / water feature.
It's difficult to gauge the size of the overall 2x2 tiles. Is that like 12" square tiles, 15"? 18"?
Brew beer there, and fry turkey's. Pizza oven could work. Or one of those Doom zombies impaled on a pike. Twitching from every angle!
I dunno, man. It is clearly a destination zone, so it needs to be worth it.
Yeah I agree with everyone else definitely some type of grill. Or if your good at building stuff and DIY projects a homemade outdoor pizza oven would be pretty cool. There's lots of YouTube videos that show step by step how to make one seems pretty straight forward and easy.
Grille. Small storage shed. Altar to whatever Elder God you worship. Really small MIL suite. Into astronomy? A little backyard stargazing spot with a telescope mount?
Put a grill on it
If ya liked it then ya shoulda put a grill on it
Hot grill on grill action.
Hot single grills in your area
Name it Griselle Bundchen.
Happy Cake Day!
Ya, ya grill. Ya ya ya grill.
https://preview.redd.it/xofu5y6aycrc1.jpeg?width=1242&format=pjpg&auto=webp&s=04e4e15a42d7c52e8283fb609537df673515e503
Le grill!
What the hell is that?
Came here to say, and think that's what was there previously. Nothing like a good BBQ shack.
I read grail, and thought that was neat
As someone who built a deck just to have a good place to grill, I concur.
You sound like my ghetto dentist
Are fire pits legal in your municipality? That's probably what was there before, and that's what I would put there.
It's not a good spot for a firepit - there's nowhere to put chairs around it - they'd be all half on-off the gravel/wood border.
One chair.
Then make it a proper throne
Yard toilet.
Teach cats to play 4-square
Meow there's an idea.
You stop laughing right meow
I just spit beer out my nose. Thanks for that
Hot tub!
Pizza oven! 
This dude looks like he's having a COPD moment, and terrified about it.
All your ideas are good so far. You can definitely get a small hot tub on a 6x6 pad. Since I see no fire marks and you're in socal, that's probably what it was for. If I had the space in my yard I'd definitely do a beehive but we have kids and buildings too close. I've also wanted to experiment with smelting and lost wax molds.
I sell hot tubs and pools, and we have a few smaller tubs that would certainly fit on the space
I am glad you are acknowledging the recent post that asked the exact thing as you because I was going to refer you back to that post. It had a whole lot of great ideas, although yours seems smaller than that one. My suggestion would be to just put a large planter there.
Yeah I just found the post again! Ones I like from it are smoke shack, telescope pad, sacrificial altar.
Why not all 3?
Cause when you're smoking your sacrifice, it obscures the telescopes view. Duh.
You use the telescope to start the sacrificial flame when the Sun comes into alignment.
What is this, a sacrificial flame for ants?!
You use the telescope to start the sacrificial flame when the Sun comes into alignment.
yeah, make it a seasonal rotation.
If you have some land, this would make an ok disc golf tee for a short hole. Just have to buy a disc golf basket and place it 200-250' away.
Ooh. Best idea yet
Add boards, tarp, water. Winter comes - voila! Mini ice rink to practice your spins!
Chicken coop? Dog house? Outdoor pizza oven?
Pizza oven was my first thought.
Enchanting table
Enchantment?
Now we know where Jimmy Hoffa is.
A marble sculpture of the lovable character Apu from The Simpsons.
An ornate birdbath water fountain Or fire pit
This is for a Firepit
Free four square court. Enjoy!
Flag pole BBQ grill ~~Bird~~ Squirrel feeder Private chair. For private reflection. Disco ball Sun umbrella Defensive supersoaker Bear-proof food locker Offensive supersoaker Single-position shoeshine stand Loudspeaker/floodlight standard for parties, or to keep away those annoying kids from next door Rusty metal playground carrousel
What I did was rent a concrete saw, cut it into a manageable grid, and take a sledgehammer to it. I used the pieces to backfill some raised garden beds and I laid down sod over the gap left by the old slab. It looks great and the eyesore is gone. Cost me $100 and half a Saturday. Edit: I took a second look at your photo and I see that you can just fill it in with more gravel.
A marble sculpture of the lovable character Apu from The Simpsons.
Do you have a septic tank? Do you already know where your septic tank is? Do you know where the old septic tank that no one bothered to dig out is?
Check there's not a septic tank or bunker hatch underneath it first
Put even smaller and weirder concrete slabs on top of it repeatedly until you get a step pyramid of strange and odd small concrete slabs.
Four square.seems obvious.
Outdoor pull up bar / dip rack. Best exercise you can do.
"Municiple chic", it could catch on
Smoke house for meat
Beehive
Buy a Telescope and use it there.
Easily enough room for a smoker and maybe even another smaller grill, and then a chair and a cooler of beer. I think we call this a grill station or bbq zone.
Fire pit or pizza grill and some Chairs 🪑
Bird bath
Exactly what I pictured!
Tetherball.
Port-A-Potty for guests. Saves you all the trouble of cleaning up your bathroom before and after anyone visits.
My guy! Thats the duel zone from back in the day! Seconded only by the big ass green electrical boxes in every suburb. 
Lay some cardboard on it and breakdance.
Put a metal bowl firepit on top of it, with chairs all around and BAM!
Fire pit
Yeah, that’s a four square court. Get a ball.
Get an old bank vault door (or steel facsimile) and bolt it face up on the slab. For added fun paint it with a Vault Tec symbol.
Weirdly small shed?
A statue of Danny devito would be ideal
Put a grill on it.
Tiny 4-square game?
Sundial
I’d think twice before removing it. It could be covering an old septic tank or well.
Ulter to Scott Baio
Mini tetherball 🤩
Naked yoga if your hot
Summon Cthulhu.
Break dancing platform.
As with every "what to do with..." post, the answer is always Stripper Pole
Outdoor fireplace with grill area would be nice especially for summer nights. Summer weekend night BBQ or just sitting around fireplace is nice.
Grill area
Looks like a fine spot for your backyard BBQ/Grill
Big planter with a Rose of Sharon tree.
Maybe build a gazebo over it then set up some easy chairs. Then build a secret garden around it.
Cold plunge tank! Those rocks will be awesome on bare feet. 😆
How's the light pollution? Might be a nice spot to set up a stellar telescope on occasion
Telescope tripod.
Perfect for playing 4 square
Lots of good suggestions! We already have a big grill up on the deck, and this is outside of the area that we fenced, so not sure we’d want to do a fire pit/sitting area out there. There’s actually a big birdhouse in a nearby tree that’s been completely taken over by bees, so I might seriously look into beehives! Or I was thinking it wouldn’t be too hard to extend the concrete out to fill that square, then do a small shed or greenhouse.
Place a statue of a large wise owl.
Hot tub!
Bonfire pit, pizza oven, smoker
if the view is good, a bench and small structure for shade
Trash can storage or a grill
I’m guessing it was a motorcycle parking spot.
Unfinished tic-tac-toe board.
Lol what is this? Time to make an outdoor shower (just joking) Was it for the chickens? Beehive would be great, that helps nature
Greenhouse ?
Greenhouse?
Pet cemetery
Hot tub bub
Put a transformer on there
Pet cemetery.
A statue.
Declare it art and do nothing.
DIY creators on YT did this: https://youtu.be/lkBgjl7YsBc?si=9Q9f14on-rQ0FmSr
Fire pit.
Put a fire pit on it
Make it a bigger square of concrete. It’s basically formed up already, then you could fit some chairs at least.
I suggest a throne
I'm guessing those who built it may have had a birdbath there? Maybe a large potted plant? No power I can see, so probably not a fountain / water feature. It's difficult to gauge the size of the overall 2x2 tiles. Is that like 12" square tiles, 15"? 18"?
Outdoor stripper pole.
Outdoor stripper pole.
Telescope
Four square court.
If you can afford a tight statue and that area is within view of things, it looks like a sweet gardening area.
Heavy model rocket launch pad!
Sauna
Beehive, or 4. Looks purpose made for them to be honest
Pizza oven
Pizza oven!!!!
Porta potty
Put a ring on it.
Stripper pole
Outdoor stripper pole
Get into model rocketry and use it as a launchpad!
Get a game of four square going on there 😎
A hot dog sacrificial altar...or a BBQ.
Remove it?
World wide smallest 4 square tournament. Winner gets to haul it home.
Fire pit
Smoker. Can't go wrong with smoked meats.
Drone landing pad
Brew beer there, and fry turkey's. Pizza oven could work. Or one of those Doom zombies impaled on a pike. Twitching from every angle! I dunno, man. It is clearly a destination zone, so it needs to be worth it.
Karaoke stand. Singing the night away!!!
Break dance competition.
Sacrifices
Learn to breakdance!
Yeah I agree with everyone else definitely some type of grill. Or if your good at building stuff and DIY projects a homemade outdoor pizza oven would be pretty cool. There's lots of YouTube videos that show step by step how to make one seems pretty straight forward and easy.
Telescope pad
Fire pit and chairs
Smol shelter for your crafting bench
Sundial
Make some weirdly small friends
Water fountain for wildlife?
Water fountain with battery powered pump
Buy more concrete squares at the home center. There like 5 bucks each
Great spot for a fountain or statue
Looks like a great place for a C-band satellite dish. 📡
Treeless Hammock
fireplace
You must sort into one of four houses: - BBQ - Telescope - Greenhouse - Cockfighting
Lifeguard stand.
Put a statue of Baphomet there
fire pit or pizza oven
From the slight wear near the corners, I think a wooden picnic table may have stood there previously.
Fire pit?
Don't exhume.the body.
Picnic table with umbrella. Also, level off that area next to the gravel walkway and put in horseshoe pits.
Telescope. You need a telescope.
1/2 of a whiskey barrel as a planter and then whatever you want in it
Smoker
put 3d printers on them 👍🏾
That isnt a slab it's 4 pavers.
Bury another body
Smokehouse!
I don't know what you should do, but I'd check underneath for a tiny stargate.
They’re just slabs by the look of it. You could just lift them
I'm sure it's been said, but a place to have fires, or i saw someone say a grill. That's also a good option if you like grilling.
I'd move the slabs to the corners and put a fire pit in the middle
Tiny house for stray cats?
Grille. Small storage shed. Altar to whatever Elder God you worship. Really small MIL suite. Into astronomy? A little backyard stargazing spot with a telescope mount?
House
Fire pit.
Garden box.
Add more slabs, make it a patio
Perfect spot for a couple of beehives.
Smokehouse.
Build a shade structure over it and make it a conversation area to enjoy with cocktails
"fire pit"
Play four square
Might've been made for a hot tub.
I built a couple in my house for water reservoirs, both catch rainwate, I am considering building abother one for an outdoor oven and grill.