'Tunnel Cam' Robot Explores 1945 Prison Escape

A secret tunnel dug and used 61 years ago by twelve prisoners to escape Philadelphia's Eastern State Penitentiary will be explored this weekend by a CRAWLING ROBOT from Envirosight. Archaeologists and historians working on the project used ground-penetrating radar to find the exact route of the tunnel under the prison courtyard, and excavated the tunnel's entry and exit points last year.