Apparently, for the Biosphere 2 project, it’s the latter option. Check out friend Geoff Manaugh’s review of the now run-down state of the facility, including some recent pictures of the site, which construction has basically been left to rot. Feral cities, indeed. Check out the glossy official Biosphere website; the pictures below tell a distinctly less upbeat story.
MICHAEL A. INNES 
So sad. It would be nice to see someone using this space.
-sarah
A sentiment I felt when stumbling across the abandoned glasshouses of the Jardino Tunduru Botanic Gardens in Mozambique’s capital, Maputo, a good few years ago. Perhaps someone has cleaned them up a bit since…
One hopes…