Advances in three-dimensional fluorescence microscopy are limited by poor axial resolution. We introduce Fluorescence Optical Nanotomography (FONT) system that bypasses this limitation by integrating widefield fluorescence imaging with serial ultramicrotomy. FONT achieves an axial resolution directly defined by the physical section thickness (40-200 nm), effectively decoupling it from optical diffraction. We demonstrate FONT's capability by reconstructing the 3D architecture of hepatocytes in rat liver and astrocytic networks in a mouse model of Alzheimer's disease, achieving a axial resolution of ∼100 nm/pixel. Furthermore, we present the design and theoretical validation of a dedicated platform that enables seamless correlation of FONT with in situ Scanning Probe Microscopy (SPM). This SPM-FONT platform is engineered to perform both modalities within a single cutting cycle, directly on the block-face, eliminating morphological artifacts. Our results establish FONT as a powerful standalone technique for nanoscale bioimaging and pave the way for a fully integrated correlative system to provide simultaneous topological, mechanical, and biochemical information from the same biological volume.