More so than the start of the new century or advent of the new millennium, Sept. 11, 2001, has come to represent the most important turning point in modern history. In an instant, the United States experienced an event so jarring that since then, Americans tend to relate dates in terms of pre-9/11 and post-9/11.

But what sometimes gets lost in today’s discourse over homeland security, emerging threats and actionable intelligence is that America’s “war on terror” is actually as old as its war for independence.

Today, the International Spy Museum opens a new exhibit that seeks to provide a historic perspective on acts of terror that have taken place on American soil. In the museum’s first special exhibit in its almost two-year history, “The Enemy Within: Terror in America — 1776 to Today” seeks to show visitors the full continuum of terrorism in the United States and, just as importantly, how American society and the government have responded to these acts over the course of the past 230 years.

It’s a history lesson on fear, a tutorial on hatred that seeks to explain the intersection of violence and political action in the Spy Museum’s own unique style.

“The methodology of terrorists is often the methodology of a spy,” said Anna Slafer, one of the lead curators and historians who worked on the exhibit. “Our role as the Spy Museum is to look at counterterrorism and internal security systems. We used specific terrorist events to do that.”

Nine major events in American history are used to depict the development of terrorists actions, public reaction and the evolution of U.S. counterintelligence efforts. These events include the burning of Washington by British troops aided by American conspirators in 1814, the march of 30,000 Ku Klux Klan members down Pennsylvania Avenue in 1925 and the Oklahoma City bombing in 1995.

“This exhibit is us looking back on American history and saying, ‘You know, 9/11 was not new in American history,” said Peter Earnest, the executive director of the International Spy Museum who spent 36 years in the Central Intelligence Agency, including 20 years in the CIA’s Clandestine Service. “The scale is new — that’s what’s so frightening about modern terrorism.

“I think people will find this exhibit disturbing,” Earnest said. “People are very disturbed by terrorism, but people also have a sketchy sense of our history of terrorism in the U.S.”

The Spy Museum creates a highly interactive experience within the 3,000 square feet of space for the exhibit, which was in development for more than a year. An audio tour takes visitors through the exhibit, activating various historical narratives along the way and allowing visitors to choose to hear more information at various exhibit features.

The Spy Museum also worked with the Gallup Organization to create polling stations that asks visitors to express their own opinions on questions raised in the exhibit. The polling stations will ask visitors if they agree or disagree with such statements as, “Violence by individuals is sometimes justified to bring about change in American society,” and, “There should be a law which bans hate groups such as the Ku Klux Klan.”

A few displays visitors will encounter on their tour, which the museum estimates will take about 30 minutes, include a children’s Ku Klux Klan robe, a replica of an anarchist’s “globe bomb” from the late 19th century and, perhaps most unsettling, a twisted fragment from one of the planes that crashed into the World Trade Center on Sept. 11.

One of the last features of the tour is an upstairs screening room where, flanked by drawings of the Twin Towers and a replica of a suicide bomber’s vest, visitors can watch an eight minute film titled “Under Siege,” which explores today’s current and emerging terrorist threats. It features interviews with Daniel Pipes, director of the Middle East Forum, Akbar Ahmed, professor of international relations at American University and other leading terrorism experts, and discusses the balance between civil liberties and national security.

“When you create an exhibit for a museum you are typically looking back, but this is history up to and including the present,” said Earnest. And as a reminder that the history of terrorism is still being written, a small cork board will hang at the beginning of the exhibit on which every morning museum staff will clip and post headlines and stories about terrorism from daily newspapers.

The International Spy Museum is located at 800 F St. NW. A separate ticket is required to view “The Enemy Within: Terror in America 1776 to Today.” For more information, call (202) 393-7789.