Heart of Darkness is about a narrated voyage up the Congo River into the Congo Free State in the so-called Heart of Africa. Charles Marlow, the narrator, tells his story to friends aboard a boat anchored on the River Thames. This setting provides the frame for Marlow's story of his obsession with the ivory trader Kurtz, which enables Conrad to create a parallel between what Conrad calls "the greatest town on earth", London, and Africa as places of darkness. Heart of Darkness has been considered for most of this century as a literary classic, and also as a powerful indictment of the evils of imperialism.