Let us suppose a world that exists under a harsh red sun. The entire planet, which may once have been fertile, is, in its current state, covered with desert. The civilization living there, which may have once been more technologically advanced, has the technology of the Iron Age.
On this desert world, water is a valuable commodity. In addition to drilling for it out of deep wells, it might be possible to recover what little water is evaporated in the air, perhaps with a device like this?
How does this thing work anyways?
How would you build a moisture vaporator with Ancient technology?
The device must operate, freestanding, in a desert, with no nearby ocean. It must be able to condense water out of the air and run it down into some sort of underground cistern for storage. To be clear, a fog fence won't work in the middle of a continental desert.
For the conditions in the desert, use any conditions that you can find in the Sahara, at least 100 km from the ocean. So, mountain ranges and oasis are to be expected and fine to take advantage of.
While I prefer an Iron Age feel, you can use any pre-industrial revolution technology necessary to make the device work.