Over the past two decades, the theory of galaxy formation has been developed and polished with the input from ab initio cosmological hydrodynamic simulations of structure formation. The simulations have made steady progress in resolution and physical treatment over the years, and finally reaching spatial regimes of 10-100 pc where more realistic interfaces with ISM physics and star formation are becoming possible. In this talk, I will summarize recent development in this endeavor, and how far the cosmological simulations have come in resolving galactic structures as a function of cosmic time, revealing the importance of feedback by supernovae and supermassive black holes in shaping galaxies.