It turns out to be the only replica of the Parthenon in the world. I read that on a bronze plaque, after I walked in the dark, serenaded by katydids who only sang two syllables of their song (they sing three most of the time in NC), and then all around and among the large pillars.
Read about the Nashville Parthenon here.
And about the Athens original here.
The original was designed in line with the Golden Mean, a proportion concept that has dominated much of Western art for millenia - apparently long before it was named and described in the Renaissance. It is approximately 3x5 (1.61) and it can be seen in numerous virtual rectangles all over the structure, from the rectangle of the facade, to the rectangle made from any three pillars in a row, to small rectangles in the ornamentation.
The replica was built on this spot in Nashville out of temporary materials, first, for a huge expo in the 1800s. It was such a huge hit that they built it again in more permanent materials. I was impressed, walking around it, lit beautifully in the dark. It appears to be made of cast concrete pieces, with lots of stone in the mix. The effect is probably more durable than the original, if not quite as lovely in texture and color.
I noticed that, like the original, the corner pillars are slightly closer to their neighbors - this was deliberately done by the Greek architect(s) to give the corner columns more visual weight, because without a neighbor on the other side, if spaced the same, they would look a little weak.