A thoroughly modern children's hospital built on old-fashioned principles

The Evelina is the first hospital in the capital to be purpose-built for children in more than a century. The last was the original Evelina, opened on a site in Southwark Bridge Road in 1869 by Baron Ferdinand de Rothschild, a member of the banking dynasty, in memory of his young wife Evelina, who had died in childbirth.

The new Evelina does for healthcare what its Thames-side neighbour Tate Modern has done for art galleries. It reverses expectations. The Tate Modern took the fear (and potential ennui) out of art by placing it in an unfamiliar scale, in an ex-industrial context. The Evelina takes the fear (and ever-threatening ennui) out of hospital care for children by placing it in a friendly, almost tactile environment. The terracotta and white building on the south bank of the Thames combines the atrium-based spectacle of a designer resort hotel with the multi-coloured warmth of a worker-friendly (even Google-esque) corporate HQ.

The Evelina's equivalent to the Turbine Hall at Tate Modern is the atrium, or conservatory - a vaulting space in a great arc of glass and steel that rises through six stories and pours light into the inpatient areas. It has views over the trees of Lambeth Palace gardens and encloses a hospital school, a performance area and the shafts of the tubular glass lifts that carry staff and patients from one colour-coded floor to another.

This emphasis on style and environment has a serious purpose: to create the hospital equivalent to a happy hotel guest or a happy website worker - a happy, secure child patient, supported by a happy, confident family. For Dr Edward Baker, the medical director for Guy's and St Thomas' NHS Foundation Trust, the hospital, which was inaugurated yesterday, has even in its first days of use proved a stimulating space, one that "distracts patients from the illness side of things".

When the design was put out to competition by the Guy's and St Thomas' foundation trust, in 1999, the trust's doctors were attracted by the entry from the eventual winners, the London-based practice of Hopkins Architects. Hopkins had never designed a hospital before, and its design reconsidered from first principles what a children's hospital should be - "a hospital that doesn't feel like a hospital".

The finished building carries all the marks of a clear brief accurately executed. Part of the brief was to involve children and parents in the design process. Andrew Barnett, one of the lead Hopkins directors on the project, remembers one child asking: "Will it feel like a hospital with those long, scary corridors?" Another wondered: "Will we be able to breathe fresh air?" These questions struck a chord with Barnett's colleague Pamela Bate, lead director on the interior of the Evelina, who during the design process found herself sleeping in a hospital with a seriously ill child. She acutely felt the lack of fresh air and sunshine.

At the new Evelina, the corridors are not corridors, but follow a gentle snaking course, with no sharp edges, and their are kaleidoscopic patterns to look at on the floor. There is fresh air, let into the atrium and the intensive care area using mechanically operated louvres. "Wherever you look," Bate says, "there is something to see and sunshine."

The hospital brings on to one site, adjacent to St Thomas' Hospital, across the Thames from the Palace of Westminster, the respective paediatric services of St Thomas' and Guy's hospitals. The new building is joined to St Thomas' at three levels by glazed bridges - "umbilical cords", as Barnett calls them - that mean a child arriving in Accident & Emergency in St Thomas' can be brought straight through into the Evelina for treatment. The intensive care unit at the Evelina (previously spread between the first and ninth floors of Guy's) is now in one open-plan room, holding up to 20 patients, where the equipment hangs on pendant arms around the beds, away from the walls, so that patients can be nursed in the round. The medical staff, Baker says, are amazed by the spaces they now work in.

Listening to Baker, Barnett and Bate, it is hard not to be struck by their shared, determined zeal for the task - zeal that is also evident in the fundraising. The hospital cost £60m: £50m is coming from the Guy's and St Thomas' Charity, and £10m from the NHS. The state-of-the-art equipment is being funded by the Evelina Children's Hospital Appeal (www. evelinaappeal.org), which has so far raised £8m of a £10m target. Stanley Fink, the appeal's chairman and the chief executive of Man Group, the hedge-fund company, shares Bate's experience of paediatric medicine; one of his children was recently seriously ill. "A sick child is a sick family," he says. And this can create strain at home.

A family deserves, Fink says, a "Marriott-style" service from the Evelina. An important part of this will be the Day Case Unit, an area where a patient can receive multiple diagnostic tests (without traipsing from one department to another), where the doctors and consultants will come to the child. The child's family will receive the results of tests the same day, in time for the child to go home to bed. Armed with these results, without delay, the family can cope better with their child's illness.

Fink is particularly enthused by the care taken to make the hospital a welcoming place. Each floor has its own colour and theme (rising through the building from the ocean on the ground floor to the sky on the sixth), so non-English speakers can use colours and logos to find their way around.

The Day Case Unit is just one part of the hospital whose performance will benefit from recent technological developments. The hospital is wireless, so a patient's records can be continuously updated centrally from remote wards or laboratories. This also means that every patient can have internet access, at a bed or in relaxation areas at the end of each inpatient floor. On the clinical front, advances in the use of non-ferrous metals means it is possible to house an X-ray machine in the same room as the Magnetic Resonance Imaging (MRI) scanner, while playing music to the patient, without any of the appliances being damaged by the scanner's powerful magnetic field.

This state-of-the-art MRI scanner was paid for with £1m given by an individual donor to the Evelina appeal. The appeal has raised funds through local and personal initiatives, from marathon running to abseiling down the daunting tower of Guy's Hospital, and it received donations from the drug giant Pfizer, the HSA Charitable Trust and other trusts. The Rothschild family, which has always maintained a connection with the hospital, has been closely involved in the fundraising.

Sir Evelyn de Rothschild, a former chairman of NM Rothschild, is president of the appeal, and both he and his cousin Jacob, Lord Rothschild, the financier and philanthropist, have given substantially to the new Evelina.

As in the merchant-banking heyday of the Rothschilds, Barings and Schroders, the City of London continues to be an important source of giving to medical charity. Most of the donations to the appeal since Fink took over as the chairman nearly two years ago have come from the hedge-fund industry. "Because the industry has made money," Fink says, "people want to give back."

Sir Evelyn de Rothschild has many years of experience with the NHS, as a former chairman of St Mary's Hospital, Paddington. He is clearly pleased at the emphasis being put on treating all patients with respect at the Evelina, and the potential of the new wirelessly updated patient records.

A journalist reporting on the inauguration of the original Evelina in June 1869 (with 10 Rothschilds and Mrs Gladstone in attendance) was struck by "the peculiar manner in which ventilation and natural light are conveyed through every section of the building... The corridors between the wards and the outer walls will afford ample space for the children to play."

By consulting parents and children, and their own instincts, the creators of the ultra-modern new Evelina seem to have taken the principles of hospital building back to those high standards of the Victorian area. Sir Evelyn says that his great-aunt Evelina, a regular hospital visitor with her mother, is remembered in the family as a "bouncy, friendly soul".

Looking around the new building that bears her name - with its helter-skelter sited in the entrance hall, bright-red lifts, colour-coded floors and the sound of music - you feel that she, unstuffy and unaffected as she was, would have approved.