The Endless City mod for 1.6.4 adds a new world type to Minecraft. This world type is an endless, abandoned city. You must try to survive in a world with few natural resources.
Download the Endless City Minecraft Mod for 1.6.4:
Endless City Mod for 1.6.4
Forge for 1.6.4
Locate your Minecraft.jar file.
Open Minecraft.jar using Winrar and delete the META-INF folder
If you haven’t already installed Forge, drag the files from the forge zip file into Minecraft.jar.
Run Minecraft once
Drag the mod .jar file into the .minecraft/mods...