Looks like a Builder was encountered. That's why he built a second Capitol and a resource silo.
And the gold came in handy, by the way (I was actually aiming for it). I desperately needed the first turn, and there was nowhere to build Archons. I saw the green and the Capitol at the purple player, but I didn't expect to see it on the grey player. I haven't seen a fully built Rampart (except for the resource pond) in a long time; I only brought him to level 2 GM.