I’ve always been fascinated by underground homes, and by grottoes natural or man-made. The attraction is not simply that of the ecologist - some contemporary eco-homes are built partially underground for insulation and to enable the new-build to blend in more readily with its environment. This plays a role for me, but is not the whole story. An aura of secrecy and mystery surround underground homes, and the child in me revels in such atmospheres. Imagine, then, an entire city underground. We tend to think of such places as backdrops for Fantasy and Science-Fiction stories, but there are historical precedents. Edinburgh had an underground city; so did Liverpool. Tourists can visit the remains of these places. Picture an entire community of 20,000 people or more, living together beneath the Earth’s crust. Fresh air is carried down via long vents. Water is conducted by underground streams, wells and cisterns. The temperature stays around a comfortable 63 degrees. Flights of carved s