heart of darkness #2 pg. 429

I think Marlow begins his tale of a journey to the heart of darkness with an account of London in "very old times, when the Romans first came here" because it foreshadows that Marlow and the crew are going to develop and colonize Africa, just like the Romans and their colonization of England.  Both London and Africa, pre-civilization, seemed foreign and savage. The Romans and the English hoped to colonize and develop the "uncivilized" regions.