Nelson Mandela devoted his life to building a more just, equal, and compassionate world, and we are all the better for it. He used his voice to speak out on the world's most pressing issues, from the HIV/AIDs epidemic, to equal opportunity and access to education, to the importance of democracy — inspiring people around the world. It was an honor to welcome to City Hall to present him with a Key to the City during the mayoralty. On #MandelaDay, we embrace his example and re-dedicate ourselves to tackling the biggest challenges we face.