Australia is delivering submarine infrastructure at a scale and to a nuclear standard it has never worked to before, across two states and four programmes at very different points on the curve: Osborne's construction yard in design, the Henderson precinct reaching its early design milestone,, estate works already in the ground at the operating base, and a contingency dry dock capability just gone to tender, with vendors circling a requirement most cannot yet cost because nobody has told them whether they can clear a nuclear safety case. Setting platform sustainment aside, this session concentrates on the built environment itself to discuss how the programmes are sequenced across two states, where the dependencies bite, and how a supply base largely new to nuclear work establishes whether it belongs in the room at all.