Apparently the ruins are all from fish tank ornaments:
“In addition to the Laager I wanted some ruins for the battlefield. These are fish tank ornaments. The doorways and stairs are a little below scale but once the pieces were glued down onto a base, stones added to connect sections and cork sheet used to add flagstones “
Thank you for the link, that’s an impressive amount of drybrushing that went into that, the cork sheet flag stones is a great idea as well.
I’ve picked up a few aquarium ornaments over the years to use for terrain but I wouldn’t have guessed that’s where the columns came from. I’ll have to keep an eye out in the future, I do enjoy ruined roman columns quite a bit.