For a couple of years, I was heavy into ATC trading, and did hundreds of them (I never do things in half measures, lol).
Eventually, I got tired of the small format, keeping track of trades, and paying postage so, as most do, I moved on–to Zentangle. Occasionally, though I find an unused ATC card, and decided to use it.
This makes me think of a temple or adobe-type dwelliings. Maybe the building in the background is where the temple staff live.