In his remarks to the 600,000-strong crowd, the pope issued his strongest denunciation of religious intolerance yet in Cuba.
He referred to the biblical account of how people persecuted by the Babylonian king "preferred to face death by fire rather than betray their conscience and their faith."
He said people find freedom when they seek the truth that Christianity offers.
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Gulf War veteran Paul Briggs' widow, Lindsey, 40, launched legal action to have his life support withdrawn so he could "die with dignity".
Rescue workers are at the site Sunday morning trying to cut open mangled coaches.
Despite chilly temperatures it will be a mostly dry day, and milder than yesterday.