This mod component allows you to specify buildings, which, if built, obsolete other buildings in the same city. "Obsoletes" in this context means, that they will replace their predecessors in the same city and prevent them from being built there again as long as the successor exists in the city.
You may build complex multilevel networks of buildings obsoleting other buildings easily by changing a certain new tag in xml. Most of the relations between buildings will be generated automatically for you. You just have to specify the skeleton. An example working stand-alone is included.
More information: Forum Thread
Version 0.1.1 for Civilization IV (Beyond the Sword) v3.17 (06/20/08)