Columbus was known for "discovering America." Though, people were already there. He was cruel to the Native Taino people and made them slaves. Once, his men captured the chiefs and burned them alive. His men also took babies from their mothers and threw them against stone walls.
http://theoatmeal.com/comics/columbus_day
This website lists the inhumane acts that Columbus and his men did. The Spaniards tortured Natives for 40 years. In 40 years, the population of the Natives went from 3 million to barely 300. Why do we celebrate a man who is a villain?