We constructed a truly nanotubular structure model of titania nanotubes based on delaminated anatase with realistic dimensions replicating those observed in experiments. It is shown that this nanotubular structure based on delaminated anatase produces an XRD pattern in excellent agreement with the observed spectrum and that the tube axis is along the [0 1 0] direction of the anatase structure. Preserving the atomic registry of delaminated anatase between adjacent layers is essential along the tube axis but unnecessary along the circumference. These understandings provide detailed information on the structure and morphology of hydrothermally synthesized titania nanotubes. The findings will help discern the complex surface chemistry of these materials.