(as for 'Skid Row')

Religious significance? No.
Mythical? No.
BC? No.
Metaphorical? Interesting question. I think it's more concrete and not as obviously metaphorical as your example. As against that, the Wikipedia article on this does include a section entitled "The P__________ as Metaphor", so the answer is clearly Yes. (I was/am more aware of the literal meaning, but it is possible that others here are more aware of metaphorical senses; I don't know.)

Yes! Following on my pantechnicon when I was last in the chair, this was Jeremy Bentham's revolutionary prison design that allows a single guard to observe all the prisoners. (It's still not clear what the single guard does when he observes all the prisoners rioting, mind you.)

*hands Raak a baton that, rather curiously, can be seen on all sides at once from a single vantage point*

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