One look at the crowd of smiling, healthy people enjoying themselves on the banks of the Limmat in Zurich does not reveal the former horror of Letten.
A decade ago, the disused railway station and tracks to the north of the city centre were littered with needles and the half-comatose bodies of drug addicts.
Letten was a victim of the drug-containment experiment that started in Zurich in 1986 but was abandoned by 1994. First Platzspitz, known as Needle Park, was opened to drug users, and when that was closed down they moved into Letten.
But early in 1995 police moved in to evict the last remaining addicts from Letten and three years later the regeneration of the area got underway. Now, the bodies lying on the ground are sunbathers and people play beach volleyball on a spot that used to be covered in rotting detritus.
One person who lived through it all is Henri Quin, who migrated to Letten from Australia in 1989.
"It was a lovely place to be at first, nice and peaceful and you could swim in the river, but that changed when the drug addicts drifted into this area," he told swissinfo.
"The place was soon swarming with them and they left their needles everywhere. My son was very young at the time so I joined a local community group to clear the place up.
Danger after dark
"I was out every night picking needles, tin cans they used to burn the drugs and foil they used to smoke it out of nearly every bush. The bridges were piled ankle high in rotting rubbish - it was filthy.
"It was no place to go alone, particularly at night and I saw addicts piled up under the Kornhaus bridge. When the police moved in there was pandemonium and the junkies panicked. They tried to run away up steep banks, but it was so muddy they just slipped back down."
After public consultation it was decided to regenerate the area in keeping with its history as a railway site. A cycle path and walkway were built along with benches, lawns, hedges, a beach volleyball court, petanque court and steps down to the river next to a restaurant.
The nature reserve also preserves the railway feel with liberal amounts of gravel and natural flora providing the perfect habitat for sand and wall lizards.
The regeneration project had five main guidelines. It had to retain a spontaneous character and not appear over-developed, it was to be an open space for nature in the city, have access to the river, retain the railway history and have a use all year round.
"Some people wanted to close the place off and forget about it, but most wanted it turned into a recreation area," said Bettina Tschander of Zurich city's conservation department. "In the end we decided to regenerate Letten as a leisure area with a design that did not change its character too much."
Plans to expand
Work was stepped up between 2002 and 2004 when the Swiss Federal Railways filled in the disused tunnel and the completed leisure area was officially opened on May 30 this year.
"In the last few years the whole area has transformed into a wonderful place for people to enjoy," said Quin, who works as a private contractor maintaining the lawns and volleyball court.
"My only complaint now is that there are too many people here because it is so nice. But all the people here are normal and are just enjoying themselves the right way."
Zurich city council estimates that up to 5,000 people a day use the facilities at weekends in the summer and there are plans to extend the project across the river, following the disused railway line all the way to the park Josefwiese, which should link the two areas by 2010.
The drug users and dealers may have disappeared from Letten, but the drug problem has not gone away, according to Ueli Spörri, general manager of Arud, a Zurich-based group that works with drug addicts.
"The area was a magnet for users and dealers from the whole of Switzerland and abroad," he told swissinfo. "When it was closed a lot of addicts went back to where they came from and the drug scene moved behind closed doors.
"The closure only made sense because it was accompanied by other medical and social measures such as methadone treatment and the opening of new drug centres.
"Because the drug addicts are not as visible any more there is a danger that people see the problem of drug addiction as being solved, and we may have more difficulty in getting support for the further development of treatment for drug addicts."
swissinfo, Matthew Allen in Zurich
Police cleared the area of drug addicts in February 1995.
Up to 5,000 people a day enjoy the leisure facilities at Letten at peak times.
The new leisure area was officially opened on May 30 this year.