What are the different types of modifications and created content I can download?
There’s a variety of material up for download. This includes user-made maps, scenarios, unit graphics, graphic modpacks (the interface), and regular modpacks (e.g. new units, rule changes, etc., but played on a random map, unlike a scenario). In the modpack forums for example, you could download something as simple as a new resource graphic to something as complete as a finished mod that adds hundreds of units and technologies! You don’t have to worry about what game of Civilization III you have, as things like graphic changes work in any version – it’s only scenarios and maps that are backwards-compatible and don’t work if it is, say, a Conquests scenario and you just have Vanilla. There are always scenario and maps for each game.