Elmina Castle (St. George’s Castle) in Ghana, built by the Portuguese in 1482, is Africa’s oldest European structure, initially a gold trading post that became a major hub for the trans-Atlantic slave trade, featuring horrific dungeons and the infamous “Door of No Return” for enslaved Africans before its eventual transfer to the British and then independent Ghana; today, it stands as a UNESCO World Heritage site, a poignant monument to the slave trade’s brutal history, and a significant tourist attraction.