The remarkable progress of large-scale astronomical surveys in the last two decades have allowed us to constrain the current cosmological model to an unprecedented precision.  At the same time, the field of computational cosmology has emerged, and evolved hand-in-hand with the observational cosmology.   In this talk, I will review the history and current status of observational cosmology, and describe how supercomputers have helped to shape our current views of cosmological structure formation.  In the field of computational cosmology, I argue that we are now entering the third revolution in the cosmological study of galaxy formation. In the latter part of my talk, I will also discuss a separate work on the accretion onto supermassive black holes, and its cosmological importance.