Theatre of Dionysus built by me, and a model of the Parthenon built by about 40 8/9th grade students in their geometry class this past October. The models are built to scale, which was the point of having students do it as a geometry activity. The only thing that is way off is the Acropolis itself, which should be about twice as big, but it would have far exceeded the boundaries of a single 256 x 256 meter region.
I'm releasing it with an Attribution-NonCommercial-ShareAlike (CC BY-NC-SA) license. For attribution you can specify "Erik Nauman and The Hewitt School" as the original creators. Only one texture is used aside from the default viewer textures and that is a white marble texture downloaded from CG Textures. The link to the OAR file is here. My students and I would love to hear how anyone uses it, so please leave a comment if you do.
Here's a video of some of the students working.