There are places in the world you simply cannot go. Not for lack of money or a visa, but because access is prohibited by law, due to real danger, or for reasons governments prefer not to fully disclose.
Queimada Grande Island, in Brazil, is home to the highest concentration of venomous vipers per square meter on the planet. The tomb of China’s first emperor has been sealed for more than two thousand years: current measurements detect mercury levels inside so high that opening it could be deadly. In the Norwegian Arctic, the Svalbard Global Seed Vault stores backup copies of seeds from all the world’s crops as insurance against a global catastrophe, and only authorized depositors can get close.
Added to that list are Area 51 in Nevada, Fort Knox in Kentucky, the Lascaux caves in France—closed since 1963 to preserve 17,000-year-old Paleolithic paintings—the Vatican Apostolic Archives, North Sentinel Island in India, and the vault where Coca-Cola keeps its secret formula. Nine closed doors. Nine different reasons to keep them that way.