Desperate signs from lost veterans in Vietnam are captured by satellite. A fleet of massive ships are stranded in the middle of a vast desert. Strange walls stretching vast distances across northern California. Just what on earth are they?
By entering your email address, you agree to our Terms of Use and acknowledge the Privacy Policy. discovery and its affiliates may use your email address to provide updates, ads, and offers.
To withdraw your consent or learn more about your rights, see the Privacy Policy.