he's due to leave that country in an hour. the focus will be on him. it's unclear whether president obama will try to visit him in the hospital or pay a courtesy visit to mandela's family. that is unclear. while he was in senegal, president obama visited a memorial to one of history's darkest times. brianna explains. >> reporter: president obama made a trip off senegal's coast to see a final departure point for slaves headed to the americas. >> the african-american president, to be able to visit this sight, i think gives me even greater motivation in terms of human rights around the world. >> reporter: peering through the door of no return is the door they walked through to board trips. the first lady is descendent