Gadol, Bava Basra first chapter goes trough all kind of scenarios.
basic rule – 2 neighbors need a wall and one can force the other to share the cost. P. 6 discusses one yard above the other. I’ll let more knowledgeable people pasken on halakha l’maaseh. In addition to stam obligations, there are also cases of hasidut and other considerations
There are several shocking stories:
A hasid that has Eliyahu coming to him, then he built a gatehouse (and stop hearing poor) and Eliahu stopped coming. My q: surely he did teshuva and took gatehouse off? and Eliahu did not return? sad…
A major amorah Ravina forces a poor nebach via a trick (sending goats) to pay for the part of the fence between them. He is reprimanded, but still shocking.
Rav Yehudah’s student who refuses to admit he learned Torah to get food during famine.