In this paper, very large computation was done to closely capture and present some of aerodynamic details of cooled gas turbine blades. For geometry side, highly complicated real world geometry of cooled turbine blade is modeled without any simplification. For grid and solution side, very thin first layer of 10-4mm was generated with smooth grid transition to the core region to adequately resolve near wall flow behaviors. From the result, firstly, rather complex flow features near end-walls and blade tip are clearly visualized and explained. Secondly, the results were further compared with those obtained from two dimensional CFD model and oversimplified three dimensional models.