My first thought as I began to read - where do they get water?
Hard to imagine that a natural water source existed 600 feet above the semi-arid land.
But, even harder to believe they carried water up the stairs every day.
slaves?
Hills and mountains even in areas where the surface is arid frequently have springs. [There is a big aquifier under the desert in Linya for example.] As for mountains, any mass has gravitational attraction- so a hill or mountain pulls the water table up from where it would be on level ground... creating the potential for artesian springs.
Probably much like how water was collected in Petra (another city carved out in the Jordan mountains) cisterns were constructed to collect flood water following heavy winter storms.
But, even harder to believe they carried water up the stairs every day.
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That’s what slaves were for.
The Nabataeans buitl and carved out cisterns and stored runoff from the intermittent rains.