【明報專訊】In my last column, I talked about the idea of underground living, which has become popular in Canada, the UK, Japan, South Korea, Taiwan and many other places. Underground spaces are often popular shopping tunnels and stylish performance spaces, suitable for cities with very cold or hot climates. Summer in Hong Kong seems to last longer and longer. In summer, humidity climbs and air pollution makes us so uncomfortable. Where are underground spaces in our city?