Cape Town is criss-crossed, underneath, by a network of rivers in tunnels. I think about 20 million litres (5 million gallons) per day flow into the sea -- and this in the midst of a water crisis. These rivers were completely forgotten after they were covered up, and rediscovered only by accident, when gas in one tunnel caused a great explosion. Now here's something interesting. My old city Church, a few suburbs removed, built two of its halls -- the Anderson and McAlpine Halls -- over a river. For years, this was merely rumoured. Some said it would explain the cold in the Anderson Hall. But no one had the facts -- until an old man came forward to confirm it. OBSERVATION: I don't know, however, how the river might flow there, if it still does.