"Even we don't know what it is," he continued. The White House, which was built between 1792 and 1800, has seen a number of changes and additions to its main building and grounds throughout the years. During WWII, a bomb shelter was built beneath the East Wing, which was subsequently transformed into an operations room. President Truman used this room to speak with generals and other high-ranking officers through a system known as "the open microphone." The White House bomb shelter was revealed by President Obama in a speech on May 20, 2011. In the speech, he said that when he first took office, there had been concerns about security after the 2001 terrorist attacks. Thus, in 2006, the federal government began work on a plan to protect the White House from future threats. The project included construction of a deep bunker located under the East Wing of the White House. Obama said that when he heard about the shelter, his initial reaction was, "They must not have told me about it." He added that he was surprised to learn that no one living in the White House at the time knew about the facility. However, later that day, Press Secretary Jay Carney announced that a presidential decision had been made to include the shelter in any future plans for the White House. According to the Associated Press, Obama's decision was based on recommendations made by Frank J. Giampoli, who was hired by the Department of Homeland Security in 2007 to review the nation's protective measures.