159 “Ground-Penetrating Radar Reveals Military Structures Buried Beneath Alcatraz Penitentiary Using non-invasive techniques, archaeologists have confirmed the presence of a coastal fortification beneath what was once the prison’s recreation yard. (twitter.com) posted 1 year ago by Joys1Daughter 1 year ago by Joys1Daughter +159 / -0 33 comments share 33 comments share save hide report block hide replies
That's really cool. This same type of radar had also found steel beam structures underneath the Pyramids in Egypt.. This world is amazing and full of mysteries. I don't think we should ever get bored!