Krakia?

If you'll notice, the sky in that picture has crisscrossing lines. This implies a dome around the area in question. The only kind of dome in masteria is the one in the electrophant map. Having a greenhouse inside a dome isn't farfetched at all, especially with the kind of technology seen in the picture.

still seems farfetched to me, it's too detailed to be inside of anything besides perhaps a cloaking device, which would explain it's absence until now.