At how far back and at which area are ya looking? Greek/Roman? Ancient China? Something else?
#Ancient City Assets
quick reef
quick reef
https://steamcommunity.com/sharedfiles/filedetails/?id=2705813363 I assume you've already found stuff like this? If you'd like more -you'll have to put in a bit of effort I'm afraid- I'd recommend looking for Renaissance or Romanesque as well, those are more modern styles but are based on ancient Roman styles so some of those assets will work as well, for example: https://steamcommunity.com/sharedfiles/filedetails/?id=1669992551 Ancient Greek may work as well since thats largely what Roman styles are based on.
This may also be interesting, depending on what you're gonna be doing: #1101273083492433941 message
(which is a generalized overview of Roman urban planning)
Do let me know if you have any other questions or if this doesn't work (well enough). 🙂