With a clear view down Pennsylvania Avenue to the Capitol and a location just a few blocks from the White House, Freedom Plaza is a popular place for tourists and protestors alike. But casual visitors may not know that they’re walking on top of buried history. The open stone plaza at 14th Street and Pennsylvania Avenue Northwest was called Western Plaza when it was dedicated in 1980. But in 1988, it was given a new name in honor of Martin Luther King, Jr., who finished writing his famous “I Have…