Pope Francis heads to Colombia next week for what might be the most grueling five days of his pontificate. He’ll visit four different cities, each with contrasting altitudes and climates, and each key to the messages he wants to convey.

When Pope Francis visits Colombia in September, he will take his message of mercy and reconciliation to Cartagena, a city that still bears scars of its painful history as a slave port. And he will walk the streets where another Jesuit, St. Peter Claver, put that message into practice four centuries ago.