Anno Domini: Brave New World is a full conversion mod for Civilization V. Set in the ancient world, it has a unique tech tree with buildings, wonders and units to fit the theme. 84 ancient civilizations are featured in the mod, all with their own unique abilities.
For a brief look at what the mod contains, click the “Brief overview” tab. The other tabs are self-explanatory and contain more detailed information about the different elements you will find in the Anno Domini world.
The download is completely free of charge, but you must already own Civilization V, both expansions and all the DLC (except for the map packs, which are optional).