Bone is an inhomogeneous, anisotropic natural biomaterial with complex, multiscale structural variations. Thus, experiments on the bulk scale using a universal testing machine are not applicable for localized precision mechanical testing of bone. Nanoscale mechanical testing technologies such as nanoindentation enables to assess the intrinsic toughening mechanism of bone, which is a function of the highly-organized matrix proteins within the mineralized nanostructure. Understanding the basic nanomechanical properties of calcified tissues will help us to appreciate general concepts associated with the excellent design of advanced engineering materials and engineered tissues.