Yeah, I too got Civ III about a month ago when it was on sale for $1.99 or thereabouts, along with Master of Orion II for like $4.99 or something.
I dabbled in Civ IV a few months ago and didn't like it. Did you know that mountains in Civ IV are permanently impassable? Can't move onto them, can't build roads over them, nothing. That's unrealistic to the point of being a game-breaker for me. Played several games where a nearby portion of a continent I was on was inaccessible because of a single mountain square. There is a quick and easy way to edit the map if this happens, but to me that's not good enough. Also, the religion thing is way overdone.
Being an old time board wargamer, the hex maps of Civ V and VI intrigue me, and I might try one of them some time, but I'm kind of tired of the Civ concept overall and Civ III might very well be the end of it for me.