The "Face" is a mile long formation on the surface of Mars that appears to be an ancient and highly-eroded artificial structure. The Face and other anomalous objects were first photographed by a Viking orbiter spacecraft in 1976, and more recently by the Mars Global Surveyor. The objects are located in Cydonia, a region lying along what many scientists believe to be the shoreline of a vast northern sea which once existed on Mars. The Cydonia Controversy provides the most complete and up-to-date treatment of the Face and other anomalies on Mars from a scientific, historical, and political perspective. It summarizes and synthesizes information from different perspectives into an integrated picture of the controversy, and presents new imagery and research results not previously available to the general public. Organized chronologically, the Cydonia Controversy:Traces the evolution of our interest in extraterrestrial life and Mars from the time of the Sumerians and Babylonians, through the Greeks, the Renaissance, to Percival Lowell and the great debate over the Martian canalsDiscusses how the debate over extraterrestrial life changed in the 20th century from a legitimate area for scientific research to one increasingly influenced by politics and concerns over national securityTells the story of how the Face and other objects on Mars were discovered during the Viking mission, and later denied by NASA, and how a group of independent investigators rediscovered these strange objects and brought them to the attention of the publicDescribes the science behind the investigation, summarizing all of the evidence for, and against, artificialityConsiders the question of whether or not the existence of artificial structures in Cydonia is plausible in light of what we know about MarsDiscusses what happened after the Viking mission, including the mysterious loss of the Mars Observer in 1993, and the successful launch of Mars Global Surveyor and NASA"s plan to re-image Cydonia in the