Fracturing processes occur at different materials length scales and naturally call for multiscale modeling. In this talk, I will present my journey on multiscale materials modeling, descended from my Ph.D. and Postdoc research association with Professor Anthony R. Ingraffea. Two critical length scales and modeling techniques will be addressed: one at the dislocation level and the other at the materials grain level. At the dislocation level, I will emphasize on the large-scale atomistic simulation: a new paradigm to study mechanics of materials in which mechanisms and properties are emerged directly from the fundamental evolution of atoms. At the grain level, a micromechanics model to simulate inter-granular fracture will be addressed.