Our group has recently demonstrated that the micro-mechanical properties of periodically arranged NCs can be significantly boosted by creating a sub-nm thin, crosslinked, organic network in-between them, using small C-18 fatty acids or phospholipids as surface functionality. The crosslinking of self-assembled organo-functionalized NCs can be achieved by thermal annealing at moderate temperatures (150 -350 °C) and allows reaching record-high values of strength, hardness, and stiffness, while still maintaining the nano-characteristic functionalities and a moderate degree of fracture toughness. However, the interactions that dictate the nanobuilding blocks' ordering during the first step of the nanocomposite's development (i.e. self-assembly) do not provide structural control at larger length scales. As a consequence, imperfections like voids, cracks, and precipitates arise, which statistically scale with the specimen's size, ultimately leading to a significant decrease up to several orders of magnitude in their mechanical response upon increasing the material's dimensions. Creating a robust, macroscale, nanocomposite thus requires an accurate structural control on several length scales and a precise tuning of the involved interfaces. A promising strategy in this direction is inspired by biomaterials. In fact, nature evolved hard and strong, but also simultaneously tough materials, such as bone, teeth, and nacre. This relates to their hierarchical structure in which mineral nano-building blocks are arranged into multiple, selfsimilar superstructures interfaced by thin, softer organic phases on each hierarchical level (HL). The fact that these biocomposites are made of simple constituents, rather unremarkable from the mechanical viewpoint when considered alone, like brittle minerals, soft polysaccharites and proteins, highlights indeed the highly beneficial effect of these intricate architectures. Following nature's design principles, we demonstrate here a new strategy to organize NCs within two hierarchical levels, yielding robust, macroscopic, functional, nanocomposite materials. We use surface-functionalized, superparamagnetic Fe 3 O 4 (magnetite) NCs as elementary building blocks, aiming at developing a bulk material with enhanced mechanical robustness, which simultaneously retains properties that are intrinsically linked to the nanoscale -superparamagnetism, in this case.