Pre-E3 Magazine Scans (24)
Screenshots that were scanned in from magazines prior to E3. Disclaimer: some of these are very old and not terribly representative of the final game.

E3 Screencaps (20)
Screen captures from the gameplay footage videos of Soren Johnson's E3 presentation released by Gamespot

E3 Press Screens (13)
These screenshots were released during E3 by IGN and 3DGamers. Note how the graphics look very different between the two sets: they are from different versions of the game.

E3 Official Screens (12)
These screenshots were released during E3 by 2K Games (on CivAnon.org) and Firaxis. Note how the graphics look very different between the two sets: they are from different versions of the game.

2005 - August (8)
Civ4 screens and art released to the public during August 2005

2005 - September (8)
Civ4 screens and art released to the public during September 2005

Concept Art & 3D Models (7)
Everything that is not an in-game screenshot: concept art, 3D models, logos, etc

2005 - July (5)
Civ4 screens and art released to the public during July 2005