Kitao's predictions came partly true in the 1950s and 60s. The city of Osaka invested in the Osaka Chikagai Co., Ltd., which constructed one new underground center after another, in areas including the Nanba and Umeda rail terminals, the Sennichi-mae and Abeno shopping districts, and the Nakanoshima and Dojima business quarters. As Japan's economy expanded, cities rose higher and put out more complicated roots under the ground.

New subterranean shopping plazas constructed since the early 1990s include Kyobashi Coms Garden, Diamor Osaka and Crysta Nagahori. Osaka now has one of the largest underground cities in Eastern Asia, crammed with restaurants and retail outlets.

The most notable feature of an underground city is that it is a labyrinth. Underground passages, stores in the basements of department stores and office buildings, and new underground shopping concourses become a complicated network of subterranean streets. If there are no maps or information panels, shoppers coming for the first time can easily get lost in the maze. And yet, the complexity and unique atmosphere actually make shopping there fun.

Designers have used a number of techniques to make shopping underground more enjoyable. For example, they lay out many imaginative common areas in shopping concourses for people to relax, and use fountains and cascading water, perhaps imitating the Trevi Fountain in Rome. At Hankyu Sanban Gai in Osaka, water is cleverly circulated to make an artificial underground river.

There are also eye-catching works of art. Perhaps the most impressive is an actual rocket that seems to soar upward from the Nanba City shopping plaza. The curtain of water rising high above floor level, with a large rainbow projected on it, is also worth seeing.

Over the last few years, architectural devices like sunken gardens and glass arcades have been used in many places to bring natural light below ground. Flowerbeds turn passageways into a kind of park. Water, sunlight, plants and other aspects of nature are used to reduce the feeling of ceilings bearing down from above.

What will underground shopping concourses look like in the future? Designers are exploring new ways to use light. Until now, underground shopping malls in Japan have tended to illuminate walls and ceilings evenly, using electric light with natural color to give the impression of sunlight. This is done in an attempt to recreate conditions above ground. In the future, though, designers will probably strive for a more natural effect using light and shade.

And they will use more than just light. They will probably develop more artistic techniques to imitate the sounds of nature, gentle breezes and natural fragrances.

Underground shopping concourses are human creations, so the designers of the past were concerned primarily with function and safety. But to be successful in the future, they will also have to appeal to the senses, while enhancing comfort and atmosphere.