Mount Elbrus is a location in 80 Days. It is highest point in Russia, located in Southern Russia, the southernmost part of European Russia.
Mount Elbrus is the site of a secret Russian base and thus is difficult to access. The base itself is an observatory, with a large mirror slung over the mouth of an inactive volcano to collect light from the stars.
After arriving with Marina Poltava aboard the Blue Flower, Passepartout and Fogg are promptly spotted by the Russian authorities and taken to the observatory where they spend the night in a cell. However, the next morning Marina's brother Pyotr arrives and releases them, offering to give Passepartout and Fogg a free ride aboard the secret military rocket-propelled underground phaeton hidden beneath the base.