Anyone can join, with a 50-word vignette in the comments. Your vignette does not have to include the prompt term.
"Down here." Tam gestured through the arched doorway. The trudging footfalls resounded as the others walked toward him, through the metallic rooms. "I wonder what led them to think they needed extra structural support, what with all these arches. And whether it would work, for support, in freefall."