Neighbor has erected a 180cm high fence without final coordination

I’m with [USER=58996]@xMisterDx on this. Possibly (based on what else is said here probably) you are right, but now the fence is there or at least "in the making," and I don’t know if I’d be willing to insist on my right against the neighborhood peace. The neighbor presumably wants a privacy screen towards you, you currently don’t want that because of more openness. Maybe the neighbor even feels accommodating because he went from 180 to 200 and is currently taking the liberty to decide more because he cares... (I do agree, however, that more coordination is needed and he bypassed that). Whether I’d be willing to fight against it probably depends a lot on how much it bothers me (how much garden do I have in total). Personality-wise, I’m more like “make the best of it,” so maybe think about what I can plant in front of it or something similar so that it looks okay to me. So possibly put a hedge in front of it, or somehow raspberries or something else on a trellis or the like, or just live with it as it is. But as I said, it’s also a personality question and I’m more on the yielding side for the sake of peace.

Maybe they want to get a big dog and need the height? But it's weird that he asks first and then just does something. Just call or ask?

Maybe he thought, ok, 200cm is too high for them, 180cm will fit... I would also find it very unfortunate that he just does it, after something else was discussed before. But honestly, I would be glad that I save the costs (for a participation he would have had to involve you, now it is too late) and plant in front of it as I please. I wouldn’t come with paragraphs and so on, then you’ll have a dispute before your house is even built. It’s not worth it. I would just keep in mind how he ticks, and otherwise continue to work towards good neighborhood relations. It might be a bad start, but you will be living close by now, so it’s good to maintain friendly relations and rather overlook such things, instead of making a big deal out of it. Maybe someday you will do something that is strictly speaking not quite right, and he will overlook it in return, or he will help you with something... That is worth more than arguing about the old fence.

2m was considered too high, now he has made it 1.8m. That will be his compromise to you. Over 1.6m I can easily look over. At least on the street side, it would be too low for me. To the neighbor, no idea. But you don't have to be able to constantly look each other’s asses in the summer. You don’t have to feel like you’re in prison, you certainly still have 3 other property boundaries.

I would simply accept the neighbor's need for privacy and let him pay for the fence alone.

You won’t get rid of him anyway. At least in this area, fences of 1.8-2m are also absolutely common.

if I want to look over there, 180 is also no problem...

I think I'm slowly starting to understand why he's building a 1.8m high fence...