America's little-known castles, displaying 'raw power,' are hiding in plain sight

Author and historian Dan Jones traces 3,000 years of fortifications in "Castles," from Fort Sumter and Fort Pulaski to the Tower of London's gruesome dark history.

Author and historian Dan Jones traces 3,000 years of fortifications in "Castles," from Fort Sumter and Fort Pulaski to the Tower of London's gruesome dark history.