About the booka classic by dan brown, the lost symbol revolves around yet another adventure of harvard symbologist, robert langdon. This one is set in washington d.c. In the united states of america.as langdon is called at the last minute to deliver an evening lecture at the capitol building, an unpredictable thing happens. When he arrives, a hideous object gruesomely encoded with five symbols is discovered at the epicentre of rotunda.recognized by langdon.