into the heart of an immense darkness

It's strange to think that this is a view of the Thames that wasn't available to Conrad at first hand (at least, to the best of my knowledge, he never went up in a balloon) - but here the great imperial river is, stretching snake-like away towards the Essex marshes.  Of course the sky was actually blue, but a combination of airplane glass and turning it into black and white makes for a shockingly dramatic contrast.

Oh - and look down to the very right hand corner.  That's Tower Bridge!

And lest you think I'm making the metaphor stretch beyond Marlow's narrative into something of my own, let me reassure you with some English roses at home in Wimbledon: today was a pitch-perfect early summer's day in the garden.