The STAR experiment has evolved significantly since it first began operation. Detector subsystems have been added, removed, and/or significantly modified between (and on occasion within) the 10 RHIC runs. Mistakes, oversimplifications and bugs in the geometry model have been discovered and addressed as simulations are confronted with ever-more-precise data. We therefore maintain over 30 distinct versions of the geometry in order to support simulation needs related to ongoing analysis, upgrade studies and historical reference.In order to help us understand the impact of geometry changes on detector response in our various simulation productions we have developed the StarBASE application within the VMC framework. StarBASE provides the capability to perform detailed comparisons of the material and medium properties between any version of our geometry and a baseline version. This allows us to perform regression tests between library releases, to ensure that changes to one part of the geometry do not have unintended consequences in another part of the geometry, and to help to quantify the impact of an evolving geometry on different physics measurements.