Innovation clusters have been the key concept underlying economic development theory and practice since the concept was re-energized in the 1990s. Worldwide efforts promoting cluster development are supposed to be informed by research on cluster dynamics. The plethora of articles and reports on this globally hyped concept often add to the confusion, calling for a systematic synthesis. In academia, the discussion of innovation clusters is characterized by separate literature dealing with agglomeration, institution, and built-environment. This literature review addresses each of those three dimensions, respectively, by discussing both classic perceptions and potential directions for future research.