This popular design proposal was originally developed as a competition entry for the Athens Olympics. The brief asked for ‘ephemeral’ structures that would facilitate hosting urban street events. We identified shaded and cooled places as the most valued spaces in summertime Athens. Our proposal was a mobile kevlar fabric cooling tower, which can be erected in 30 mins. Helium is pumped into a torus ring, inflating it to form the top of the tower, which lifts to above the pollution level in Athens. Water is then pumped up small veins sown into the fabric of the tower, and weeps out of holes to run down the inside skin. This water evaporates, and the effect of this, known as evaporative cooling, is to draw clean air down the inside of the tower, cooling it by up to 12 degrees. The patterned surface of the fabric casts event shadows, and together with the cooled clean air, these define an ephemeral architecture of shade and air. At night, the process naturally reverses, and warm, polluted air from the surrounding city streets is drawn up the tower and dispersed at high level.