That's a new one... I'll look at it. I'll look into this, too. EDIT: Well, that was an easy fix! To make Silos buildable, go into CIV4BuildingInfos.xml, find the Missile Silo code, and change: Code: <SpecialBuildingType>SPECIALBUILDING_BOMB_SHELTER</SpecialBuildingType> to: Code: <SpecialBuildingType>NONE</SpecialBuildingType> This was old code left over from when the Manhattan Project was a Project instead of a National Wonder. I just forgot to change the affected XML. By doing this fix, you will be able to build Missile Silos. This fix will be included in patch v3.19b when I get around to it. Thanks for finding this error, Dimoncheg! Nah, I think I'm going to leave the Scientific trait as is. I think you're just too good at playing Civ.