New York City, September 24, 2007—Thousands gathered at Columbia University to protest the appearance of Iranian President Mahmoud Ahmadinejad.

Ahmadinejad spoke by invitation at the university while in New York to address the United Nations.

School officials were under pressure to cancel the appearance, because the Iranian leader had previously described the Holocaust as a "myth" and repeatedly declared his antipathy for Israel.

Ahmadinejad spoke as planned, however, calling for "purity of spirit" in academic research, condemning Western nations' "misuse of science" in creating weapons, and citing a need for "sufficient research … from different perspectives" on the Holocaust.

University President Lee Bollinger said hosting the event was "the right thing to do, and indeed it is required by the existing norms of free speech."

• More Photos in the News
• Today's 15 Most Read Stories
• Free Email Newsletter: Focus on Photography