Without cheesing with things like Maritime CS's and multiple internal trade routes? I had 47 on Persepolis the turn after I won (around 350 on Standard) I had only one Internal trade route and that was after it hit Pop 40. My second city Pasargadae is also the biggest non-capital I've had without cheesing, both in the same game on a Sandstorm map! Sun God helped a lot, I had 2 Flood Plain Wheat in Pasargadae and 3 plain wheat in Persepolis. The only food-related wonder I had was Temple of Artemis. Could've been higher had I gone Freedom too.
I've hit 100+ in cities like Venice abusing trade routes and buying out all of the maritime CS's, and also had Hanging Gardens and Temple of Artemis stack.