If you're heading to West Africa to unearth lost treasure, look no further than Benin. This club-shaped country, on the western edge of Nigeria, was once one of the most powerful empires in Africa - the Dahomey kingdom. The ruins of the Dahomeyans' palaces and temples can be seen in Abomey, while Ouidah is a poignant reminder of where their riches came from: the slave trade. The Route d'Esclaves in Ouidah was the last walk on African soil for slaves bound for Brazil and the Caribbean. Museums...