In this monograph I briefly review some highlights in the evolution of gravitational theories from ancient times through General Relativity and the MOND/Dark Matter controversy. Then I introduce a new theory of gravity based on Observer Physics, an approach that brings the observer viewpoint into recognition as a key player in the game. I suggest a new interpretation of Newton's and Einstein's approaches and some new ways of looking at gravity's geometry that imply unification of gravity with EM and QM (via phase conjugation techniques) and a theoretical approach to resolving the MOND/Dark Matter issue.