It cost pounds 2m to build, sells almost anything from socks and clothes to food and jewellery, and comes with a guaranteed captive audience of potential shoppers, from the hospital staff to patients and visitors.
For decades, hospital concourses have had the so-called "flowers and Lucozade" stalls, often run by the Women's Royal Voluntary Service, selling a limited number of lines aimed mostly at the market for last-minute presents for patients.
Traders, however, have discovered that, with major hospitals such as the University Hospital of Wales, which employs 12,000 people, patients and visitors have all the commercial potential of a small town.
Developers who are working with NHS trusts on another six similar complexes say that major supermarkets will also soon be setting up shops in the centres being developed at major hospitals, including Cardiff and the 1,100-bed Queens Medical centre in Nottingham.
Retailers so far involved in hospital shopping include Sock Shop, Body Shop, Stock Shop, Burger King, Pizza Hut, John Menzies, the Post Office, Boots and NatWest, as well as jewellers, hairdressers, newsagents and florists.
The centres are being built mostly under the Government's Private Finance Initiative (PFI), where private developers such as HealthGate build the complex, take the rents from the shops, and then hand the building over - free of charge - to the hospital after 25 years. The hospitals take a share of the profits above a certain agreed level, and this can then be spent on services.
"They can't lose, really. The hospitals get a new entrance. They get space freed up inside. They get good shopping facilities for staff, patients and visitors. They don't put a penny in, and we take all the risks," says Nick Elkins, the development manager for HealthGate, which has another smaller centre at Nottingham. "We see a day when the likes of Tesco will have small stores in these centres."
"There are, we believe, three places that guarantee a turnover: airports, railway stations and hospitals. They provide a recession-free environment with no competition," adds Elkins.
He says the big push on hospital development has been made possible by PFI. "Hospitals are there to treat people who are ill, not to spend money on building grand entrances with centres like these. With PFI, they have everything to gain," he says.
Other hospitals such as Stirling, which is expected to have a new Sock Shop soon, Southampton, and the Chelsea and Westminster also have shops but have not developed the full retail centre idea.
Boots plan to open two shops in hospitals and Sock Shop is looking at other sites too. One clothes retailer, Stock Shop, has eight hospital outlets, while John Menzies has also been increasing its presence.
"Cardiff is a big hospital with a lot of people passing through and it is a site that appealed to us. We decided this year to try out hospital sites and we are pleased with the progress," said Susan Jones, marketing manager of Sock Shop.
In most of the developments, visitors and staff walk through the shopping centre to get into the hospital, making the shops prime retail sites. Concentrating the retail business in the new centres also means that areas of the hospitals previously used can better employed in improving patient care.
Early research at Nottingham has shown that approximately 80 per cent of the people who used the shops were hospital staff, and HealthGate believes that around 3,000 of the people who will walk through the new centre at Cardiff every day will be nurses.
It is also likely that the centres could be used by local people taking advantage of the high-quality shopping facilities.