Obtain a demolition order against yourself?

Clear conflict of interest. What does he want to give you for the property and what does the market offer you for the property?

That the neighbor agrees that you sell to him and grants you a right to participate in a resale?

I can only say again, he is not interested in a sale, no matter how, he does not want to sell now and also not in the future.

He would have offered me €60,000 for my site, the market would easily provide €140,000.

The neighbor is about 65 years old.

Would he be willing to start demolition early if you cover the demolition costs completely or to a large extent?

Hmm, this is really tricky. I would also try it through the [Behörde]. Just be open and talk to them. They can't be interested in the disgraceful sight either.

Aha. He wants to buy your part cheaply and then make a profit.... Way: We sell together for say 250 thousand. And share the profit. For 280, if we first demolish together what could be done for 20. Each 10....

Oh man... How many times do I have to say, he does not want to sell. He also does not want to buy ours anymore. He just wants to leave everything as it is. That's exactly the point, there is nothing to hope for any kind of agreement.