Their example renders look really, really good, but that's mostly due to the artist's nice stone texture, which he did NOT supply or link. Each OBJ mesh is quite low-poly, you have to 'skin' them yourself. My artistry is minimal, I'd rather not craft UV maps, so I went hunting for seamless ashlar textures.
Google Images found...
http://micastoneworks.com/
http://micastoneworks.com/resources/seamless-stone-textures/



They really are that good, and they're on a fast server. I downloaded a bunch of Medieval-ish stuff...
Will they suit that pack of ruins ? Don't know. Now ~0230 local, and my wits are ebbing...