Architectured materials includes lattice materials and foams, but also dense materials composed of building blocks of well-defined size and shape. While the deformations of the blocks typically remain small and within elastic limits, their interfaces can channel cracks, slide, rotate, separate or interlock collectively, provide a wealth of tunable mechanisms. In this talk I will outline some striking analogies between emerging architectured materials and hard biological materials such as bone, teeth or mollusk shells. I will also discuss how we are duplicating these architectures from the top down, by carving weak interfaces within the bulk of hard materials such as glass or ceramics. This architectured / bio-inspired approach leads to materials with highly unusual combinations of properties which usually conflict: High stiffness and high toughness in a nacre-like glass, hardness and flexural compliance in fish scale-inspired coatings.