US First Lady Melania Trump is touring a former slave fort in Ghana on the second day of her four-nation solo trip to Africa.

Tens and thousands of enslaved Africans were held in the fort at Cape Coast, one of several along the coast of West Africa, under degrading and inhuman conditions before being shipped across the Atlantic.

Former US President Barack Obama in 2009 described it as a matter of profound sadness but also a place where the history of African-Americans began.