The theatre organ that Cameron Carpenter uses on his "Cameron Live!" DVD/CD is located in Great Falls, Virginia near Washington, DC :
The reconstruction story is very detailed.
An entire building was built for the organ console and pipes. My understanding is that the local zoning board would not allow the owner to build a new structure that was bigger than his house, so the organ "barn" was built as an addition (connected by an enclosed corridor) to his existing house.