President Ahmadinejad of Iran spoke at Columbia University on September 24, 2007 to a less than welcoming crowd. See this quote from MSNBC.com:

"On Monday, Ahmadinejad, speaking at Columbia University, defended Holocaust revisionists and raised questions about who carried out the Sept. 11 attacks. Thousands of people protested his visit. He also denied all the chief accusations against Iran: that it is providing weapons to kill U.S. troops in Iraq and Afghanistan, supporting terrorism or breaking international law by developing nuclear weapons."

New York Cool photographer Angelo Rivera was on hand and he got these photographs.

Crowd of Students on the Great Lawn of Columbia University