Terrace wall to the neighbor - What should we consider?

So my question:

Am I allowed to build 2m high and 4m long at my border to the neighbor? Do I have to pay anything to the neighbor? What rights and obligations do I have? Do I have to build on the border or is it possible as described above?

May I build 2m high and 4m long on my border with the neighbor?

No.

Am I legally bound to anything?

Yes, see #7, 17 .. we already covered everything, the reader just has to understand it sometimes.

1.80 is probably, as everywhere in the LBOs and neighborhood laws, the limit on the property border and must therefore suffice!

Check neighborhood law and statute ;). Or development plan. Or city ordinance.

I cannot share something with the neighbor.

You share with him a house wall, a garden border, and thus your life with him.

We have tried everything but the neighbor is antisocial

What do you mean by that? Just because he doesn’t want what you want, is he antisocial?
For me, the antisocial one here would be the person who insists on enforcing their own will even though they bend the laws by doing so—someone who cannot adapt to the regulated norms because that would be unsocial.

My personal opinion on this situation: I find it quite crazy and exaggerated to get so worked up about these few centimeters that you can’t even write a proper sentence in a forum anymore. Well, let your husband be 1.90m. That does not automatically mean that Mr. Müller is looking over the wall or can look over it. I assume he has his own life to manage rather than dealing with you. HE wants it right, and that’s good. A middle terraced house always has a few more disadvantages outdoors than the end terraced houses. You don’t need to be overly considerate toward the middle Müller, but that doesn’t mean you can just throw out that childish “I want, I want.”
My tip: Maybe you should start looking for a single-family house in due course.
This can’t go well with you.

No. Yes, see #7, 17 .. we already covered everything, the reader just needs to understand it sometimes. You share a house wall, a garden boundary, and thus your life with him. What do you mean by that? Just because he doesn't want things the way you want, is he antisocial? For me, the antisocial one here would be the person who absolutely wants to impose their will even though that means bending the rules – someone who can't adapt to the regulated norms because that’s not social. My personal opinion on this situation: I find it quite crazy and exaggerated to fuss so much about these few centimeters that you cannot even write a proper sentence in a forum anymore. Well, let your husband be 1.90m tall. That doesn’t automatically mean that Müller can or will look over the wall. I guess he has his own life to manage rather than to deal with you. HE wants it properly done, and that’s good. An average terraced house always has slightly more disadvantages outside than the end terraced houses. You don’t have to be overly considerate of the middle Müller, but that doesn’t mean you have to throw out this childish “I want, I want.” My tip: Maybe you should start looking for a single-family house in good time. This can’t end well with you.

So I googled myself now: If one wants a fence, I can put it up on my property. I’m allowed to build the fence up to 180 cm high at the boundary (not directly on the boundary) without spacing. Then I can build a wall up to 180 cm at the boundary, from 2m I need the neighbor’s consent, sorry actually from 181 cm already if I want to build on or at the boundary. I can build 2m high but must keep a 50 cm distance. I just looked it up and this applies to Rhineland-Palatinate. Where have I said “I want, I want”? I build the wall thinner although I wanted it wider, shorter 3 instead of 4m because Müller wanted it, deeper because Müller wanted it, on the foundation that I wanted to renew but Müller wanted it that way; as the only compromise I insist on the 5 cm, that is also my good right and healthy to set boundaries when it’s too much for me. Müller has a sliding door on the middle house and now complains because it doesn’t want to be bricked up, but that’s not my problem. I also paid considerably more so that I have the corner house. Furthermore, they grill and smoke at the boundary; everything blows over to me, I want peace. He already built his terrace and basically has little or less space on his property and wants to build it exactly in the middle so that he doesn’t feel cramped. I am accommodating him. I have a huge property; I could have paid for the whole wall and built it completely on my property, but he earlier already, without agreement, laid the foundation for his terrace on our property, so I won’t respond to the accusations anymore. I will try to find the relevant paragraphs and add them here from the info I have above.

Take a look here in the on neighborhood law from the responsible ministry. There is also a section on dispute mediation included. And the regulations at the state level.

For walls, etc., local rules then apply as mentioned above, which are referenced in the brochure.

Good luck and all the best to you and your neighbors.

May I, as a mid-terrace house resident, briefly make a comment?

I find the whole attitude strange:

Furthermore, they grill and smoke at the border,

Yes. Where else in a terraced house? We and all 5 neighbors do that too (two of them smokers). In summer, at least one grill is on every evening, and everyone notices.

I want peace.

Then why a terraced house? Regardless of whether corner house or middle position, "peace" in the form of seclusion from neighbors simply does not exist here. But you know that beforehand, don’t you?

It is also my right and healthy to set boundaries when it is too much for me.

Actually, it is not your right. If the law states 1.80m, your right is 1.80m. Not 1.85m and certainly not 2m.

We also have 1.80m; the developer of our row placed that between the terraces from the start, over 3.2m length. If the neighbors left and right had wanted 2m high and 4m long, they could have wanted, but would not have gotten it.

I have a huge plot, they could have completely paid for the wall and built it on my plot, but earlier, without consent, the foundation was already laid as his terrace on our plot

Which is indeed cheeky and not allowed. But the following is a misjudgment:

Müller sliding door the middle house is crying now because it doesn’t want to be bricked up, but that’s not my problem.

Yes, it is your problem. Because as a terraced house resident you simply share some problems. He will insist on every legally recordable cm, and obviously THAT is also your problem, since you want more.

I have a huge plot, they could have completely paid for the wall and built it on my plot,

And that would still be possible if you did not want it higher than allowed, as I read the whole discussion so far.

Otherwise, I read a lot that suggests you are not the terraced house type at all, yet you bought a terraced house anyway.

Here is a picture from the neighborhood, where the wall extends under the floor, i.e. well over 180cm. I would have to check again, my husband just sent it to me, whether it is 2m or 220, I'm not sure. And where is the problem as a middle house?

This is customary here! Furthermore, I grew up in a middle house, but as I said, I will not justify myself on the subject of neighbors, that I make enough compromises. 2m is customary, the development plan still applies, it is stated there as well, I just checked.