Bone architecture as size and shape is important for bone strength and risk of fracture. Most bone loss is cortical and occurs by trabecularisation of the inner part of the cortex. We therefore wanted to identify determinants of the bone architecture, especially the area and porosity of the transitional zone, an inner cortical region with a large surface/matrix volume available for intracortical remodeling. In 211 postmenopausal women aged 54-94 years with non-vertebral fractures and 232 controls from the Tromsø Study, Norway, we quantified femoral subtrochanteric architecture in CT images using StrAx1.0 software, and serum levels of bone turnover markers (BTM). Multivariable linear and logistic regression analyses were used to quantify associations of age, weight, height, and bone size with bone architecture and BTM, and odds ratio (OR) for fracture. Increasing age, height and larger total cross-sectional area (TCSA) were associated with larger transitional zone CSA and transitional zone CSA/TCSA (standardized coefficients (STB)?=?0.11-0.80, p = 0.05). Increasing weight was associated with larger TCSA, but smaller transitional zone CSA/TCSA and thicker cortices (STB?=?0.15-0.22, p?