I believe the reason there is confusion about this structure is from several articles that were very badly written, such as the Suite 101 article. It made huge mistakes such as the name of the Campus Martius and the wrong statue labled as Pompey....it's actualy Augustus.

The building has not existed for centuries and information can be difficult to confirm, however much has been acurately written about the structure and all one really needs to do is read, read, read. Then you can compare information and figure out what is correct pretty easily.