I'm not sure which is worse, the maximum security height cement prison wall or the hideous pile of rocks beside your swimming pool. Gaak!

Is there any open earth to plant in between your pool and your wall or between your wall and the neighbor's maximum security version? If so. vigorous vines like Star Jasmine, Wisteria and Crossvine may work. If you have no soil to use, ask the neighbors if you can paint a mural on the back of the wall. That may be your only hope from what I see.

And for the hideous pile of rocks beside your pool, may I suggest a whole flock of penguins instead of one lonely owl or several large potted palms and a few flamingos.

How thick is your fence? Can you add a row of planters. Or maybe you can built some sort of narrow structure and add some greenery.

I like rmsaustin’s suggestion. Find out if the neighbors high wall is within your city’s code, or not. It looks too high for it to be within code.

Call Code Enforcement in your area.

Is that just a wall or the beginning of a building? Why would there be a fence (besides the OP fence, then a wall like that? If it's just a fence/wall and it allowed by code, at least they've preserved your privacy. If it's a beginning of a building...you're going to have much bigger complaints.

Take your first photo and a plate of cookies, knock on your neighbor's door, and ask if they could help you out by painting (or letting you paint) the cement blocks maybe a nice light-ish blue to blend with the sky. Or a colorful mural, if they seem like the artistic type.

Are those rocks a waterfall? I see pipes in there & the flat rock extending over pool looks like the fall. And, curious, what was the conversation that must’ve been had while this wall was under construction? It didn’t go up overnight….what is purpose for wall on the other side?

I'm thinking there is an elevation change going on. The last picture, right corner, shows a white metal fence on top of the boundary wall.

The neighbor's maximum security wall is two tiered. The lower retaining wall is for making a level lot. The upper wall is the fence wall at ground level. Beth will be lucky if there is sliver of setback that can be planted in. VINES! In Cali you can do Creeping Fig.

I noted that right corner but couldn’t understand what it is. If next door neighbor is at a much higher elevation, I wonder how far back on that lot the house sits? You’re right about creeping fig! Grows fast & doesn’t destroy the masonry etc that it attaches itself to. And, it’s very flat not sending out huge aerial shoots!

Christopher, I can see now what you're saying and I'll bet you're right. I just hope for the OP sake that there isn't going to be a 3 story house built up there that will block the sky. Would be nice if the OP checked back in.

Vines. Climbers, espaliered trees. In a word,cover it wwith greenery.

Is there enough soil space between your fence and the pool to plant? I completely agree with the suggestions for using greenery and plants if at all possible. Not sure if one of olychick's pictures is bamboo, but I've seen that recommendation before for narrow spaces where you want a lot of greenery and height without much width. If there isn't already space, you might need to build planters.

Bamboo!

Bamboo is great - fast growing and there are varieties for almost every gardening zone. They are invasive but that doesn’t appear to be an issue for you. A few well-placed plants and you’ll soon have a beautiful screen. There are some excellent online growers who can help you with selecting the best variety for your yard.

Normally I hate bamboo with the passion of a thousand suns. That stuff is the work of the devil.

However in this case I agree it looks like it can't really do much of its invasive proliferation on the OP's side anyway - and hey, it might be amusing to think it's tunneling under that hideous wall and popping up on the neighbors yard all over the place. :)

Thanks everyone for ideas. Yes, that is a waterfall on edge of pool. Home is in Az. We went north in May and they had just started digging and bringing in fill for lot.Long story short , our neighbor was sending pictures of progress once a month. We got home two weeks ago and photos , we knew it was not good,but until you are standing looking at it in your backyard or looking out your slider doors from living room ,dining room or bedroom you have no idea. We will start process of getting estimates for some of your ideas. But we will get permission from our new neighbors who put wall up before we do anything .

Is there going to be a house behind/above that wall?