A dilapidated two-century-old building in Saint-Louis, Senegal bears testament to the island's little-known past as part of the transatlantic slave trade, the traces of which are quickly and quietly disappearing from view.

Located in the country's north, between the Atlantic Ocean and the Senegal River, the island is rarely mentioned in the history of the slave trade, even though it was a hub through which tens of thousands of Africans passed, according to historians interviewed by AFP.

Saint-Louis was France's first trading post in sub-Saharan Africa, established in 1659, and served as the former capital of the French colonial empire in west Africa.

It was also a holding point for captives, before shipment onward.

However, its role has been more muted compared to Senegal's famous Goree Island off Dakar, which has become a major symbol of the slave trade thanks to its House of Slaves historical site and museum.