Perhaps Lego would consider an "Antiquities" theme? I think Lego designers could do a phenomenal job with this.
To better market this line, I would suggest making this a "large exclusive" line as it would primarily appeal to AFOLs, and release one per year similar to the Winter Village theme. Set options could include Sphinx, Colosseum, Acropolis, Tower of Babylon, Great Wall, etc. Each would include 2-3 era-specfiic minifigures to round out the set, and set sizes would be 1,500 to 2,500 pieces each.
I have no doubt AFOLs would snap these sets up, similar to the Large Scale Models like Taj Mahal, Tower Bridge, etc.