Barack Obama, the first US President of African ancestry, has visited Goree Island in Senegal -- the point of departure for the slave trade.

The US first family visited the House of Slaves, a fort built in the late18th century as a transit point for human traffic.

The visit was a sombre reminder of a shameful period in US history. It provided a powerful contrast between Obama's stature as leader of the world's most powerful nation and the historical status of Africans, once treated as property in the country he governs.

The Obamas today fly to South Africa - the second stop on their week-long tour of the continent.