The three-dimensional (3D) grain boundary (GB) network of two conventionally manufactured 316L stainless steel specimens and one grain boundary engineering (GBE) processed specimen were investigated and compared quantitatively using serial sectioning and electron backscatter diffraction mapping. The analysis concentrated on the topological arrangement of twin boundaries in the GB network, including triple junction, quadruple junction, and twin-related domain. While GBE resulted in modest improvements in triple junction and quadruple junction character distribution, it significantly increased the proportion of triple junctions containing two twin boundaries and quadruple junctions containing three twin boundaries, enhancing resistance to intergranular degradation. The GBE-processed material exhibited large twin-related domains with complex tree-ring shaped twin-chain structures, whereas the conventional material contained smaller domains with simple tree-shaped twin-chains.