NEW YORK (CBSNewYork) — A special tribute was held in Manhattan Tuesday night to mark the 50th anniversary of Dr. Martin Luther King’s final speech.

Mayor Bill de Blasio lit the arch in Washington Square Park as dozens of people gathered to listen as audio of Dr. King’s “I’ve been to the mountaintop” speech was played in its entirety.

In his 1968 speech in Memphis, King called for unity and non-violent protests the night before he was killed.