Advisors, Diplomacy, Misc (70)
Images from the advisors screens, as well as some miscellaneous shots

In-game (59)
in-game screenshots, including the city screen

Play the World (55)
Images from the expansion pack

Units: Images from Screenshots (5/37)
Snapcase's terrific work isolating unit images from screenshots. Names are either confirmed or guesses
Ships, Infantry Units, Cavalry,
Artillery, Tanks

Leaders (18)
The Civ3 Leaders as you will face them during diplomatic negotiations

Conquests (18)
Screenshots from the second Civ3 expansion pack

Units: Firaxis' Images (15)
The first unit art to be presented, posted exclusively on Apolyton on December 2000, along with more images posted later

Play The World (Oct 2002) (15)
Latest images from the expansion pack