Bava Batra 6 - Privacy on the Roof (Civil)
If two homes are standing on two opposite sides of a public domain, both owners must make a fence of four amot (about 6 feet) high across half of their roof. The fences must not be directly opposite each other. Instead, each must cover the adjoining side, preventing his neighbor from looking directly into his roof and preventing him from looking into his neighbor's roof. Furthermore, the fences must be slightly longer than half the roof, thus further obstructing the view.
It would be impractical for each owner to build a fence and unenforceable to require only one owner to do so.
Even though one owner can say, "What difference does my fence make? The public sees you anyway?" - the other one can reply, "I can hide from the public by doing my private acts at night, but I can't hide from you."
Art: Rooftops in Naples by Thomas Jones
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