Which speech contained the line "tear down this wall"?

The correct answer is the Brandenburg Gate Speech. This speech was delivered by President Ronald Reagan on June 12, 1987, at the Berlin Wall, where he famously challenged the then-General Secretary of the Soviet Union, Mikhail Gorbachev, to "tear down this wall." This moment has since become iconic as it symbolized the demand for freedom and the eventual end of the division between East and West Berlin, and, more broadly, the Cold War.

The other options do not contain this phrase. The Berlin Address is not a widely recognized title for a significant speech made at the Berlin Wall. The Gettysburg Address was delivered by Abraham Lincoln during the American Civil War and focused on themes of unity and equality. Washington's Farewell Address discussed issues related to national unity and foreign alliances but had no connection to the Berlin Wall or the Cold War context. Thus, the Brandenburg Gate Speech stands out as the correct answer due to its historical significance and the specific wording of that line.