It never stops. It's unique in many respects - not only the largest, but one of the highest cities in the world at 2,205 metres above sea level, surrounded by desert, mountains and one or two active volcanos. Plus, it's sinking - about four centimetres a year. Life here is a puzzling mix of chaos and laid-back lifestyle. Almost every driver honks his way through the maddening maze of city traffic, but there is no evidence of road rage.
Friends greet each other with hugs and kisses.
So do the women. Street vendors offer incredible deals on everything from fresh mangos to silver jewellery to wool blankets. It's a place of endless commerce apparently unhindered by business bylaws. And lunch lasts two hours. Now that's civilization.