The Navy is trying for a third time to enlist the private sector to redevelop the Portsmouth Naval Shipyard’s shuttered prison, a fortress-like structure that has priceless views of the Atlantic Ocean but needs millions of dollars of repairs after years of neglect.

Dating back 106 years, the prison on Maine’s Seavey Island in the Piscataqua River separating New Hampshire and Maine features medieval architecture with turrets that give it the appearance of a castle overlooking Portsmouth Harbor and the North Atlantic.