Lost City is located in the North Atlantic Ocean on the seafloor mountain Atlantis Massif, which is approximately the size of Mount Rainier. The site is described as a long-lived vent field, estimated to be older than 120,000 years by radiocarbon dating the oldest chimney deposits of the field. However, this is significantly younger than the age of the Atlantis Massif itself, which may be as old as two million years. Lost City is located on a shelf approximately below the massif summit at a depth of around , with an approximate area of . The massif itself may have originated in a similar manner to many other ocean core complexes.