Blair House is located on Pennsylvania Avenue in Washington, D.C. It is one of four residences that make up the President's Guest House. It was constructed in 1824 and purchased in 1836 by newspaper publisher Francis Preston Blair, founder and editor of the Globe. His son, Montgomery Blair, Postmaster General under Lincoln, inherited the home from his father, and was most noted as the attorney for Dred Scott. It was here that General Robert E. Lee was offered command of the Union Army, an offer which he turned own. The house would remain in the family until 1942 when it was purchased by the U.S. government. The Blair family had leased the property to the government prior to that. Harry S. Truman spent much of his presidency living at Blair House while the White House was being renovated. On November 1, 1950, while Truman was upstairs napping, two Puerto rican activists, Oscar Collazo and Griselio Torresola, attempted to gain access to the house and assassinate the president. They were confronted outside by White House Police and a gunfight ensued, during which both men, along with officer Leslie Coffelt, were killed. By the early 1950's Blair House was merged with the Lee House next door. The Lee House was built by Francis Preston Blair in 1859 as a home for his daughter and son-in-law, Elizabeth Blair Lee and Samuel Phillips Lee. In the early 1980's the Blair-Lee House was then merged with the Peter Parker House and 704 Jackson Place to form the President's Guest House, which is used today to house foreign dignitaries and former presidents when they visit Washington. Guests have included Margaret Thatcher, Charles de Gaulle, Queen Elizabeth II, Boris Yeltsin and Vladimir Putin. The Blair House was declared a National Historic Landmark in 1973. There are several plaques on the front gate to the complex.