You mean, ruined versions of existing buildings? You'll find some of them among Ujimasa's resources, e.g.:
Barracks (Human) and Derivatives Edited by Ujimasa Hojo Barracks (Human, Optimized) Info: Polished some texture wrapping around meshes especially among the Birth ones. Uploaded. Barracks (Dalaran) Info: Created a Barracks which meshes well with the Arcane Observatory. Cleaned...
www.hiveworkshop.com
Workshop and Derivatives Edited by Ujimasa Hojo Workshop (Optimized) Info: Deleted some of the redundant meshes. Fixed up the texture wrapping of the base. Uploaded. Workshop (Dalaran) Info: Created a Workshop which meshes well with the Arcane Observatory. Redid the texture...
www.hiveworkshop.com
Search "<your building> and derivatives" for more.