The French tricolour flutters over the giant steel gate of La Sante prison. The words "Liberte, Egalite, Fraternite" are etched in its stone portal. Plaques outside the fortress, which covers an entire city block, commemorate members of the French Resistance who were imprisoned and often executed here during the second World War.
For many Parisians, the 133-year-old penitentiary just a few blocks from the stylish brasseries of Montparnasse is a part of French folklore. Public guillotinings were once carried out here. The poets Paul Verlaine and Guillaume Apollinaire, the painter Douanier Rousseau and the first president of Algeria, Ahmed Ben Bella, were famous inmates. More recently, the Venezuelan assassin, Carlos, and a clutch of corrupt ministers and corporate executives joined the list.
Yet virtually nothing of the reality inside the ill-named La Sante's sooty, 10m-high walls reached the outside world. (Sante means "health".) Repeated requests for visits by leading French newspapers were turned down. It took an insider, the head of La Sante's medical service, Dr Veronique Vasseur, to break the silence.
Dr Vasseur's book, Head Doctor at La Sante Prison, will go on sale in French bookshops on Friday. But excerpts published by Le Monde have already provoked an outcry, and the admission by the French Justice Minister, Mrs Elisabeth Guigou, that "the situation in many of our prisons is not worthy of a country like ours".
When Dr Vasseur joined La Sante's staff in 1993, she found cockroaches swimming in disinfectant containers in the infirmary.
Since then, she concedes, the infirmary has improved - but little else has. She had to ask inmates to collect bed-bugs in urine sample jars before the prison administration replaced their vermin-infested mattresses. Many of the 1,236 prisoners still stuff clothing around their cell doors in an attempt to keep the rats out.
Four men inhabit cells measuring 10 square metres. They are allowed to have only two showers per week, unless the prison doctor prescribes additional showers to treat their frequent skin diseases. The communal showers are covered with green mould.
The violence described by Dr Vasseur is as shocking as the filth. One night she found a man naked and trembling, "curled up like a snail in a pool of blood" on the floor of an isolation cell. Eight guards followed her and the man whispered: "They are the ones who did this to me."
Most of the violence done by inmates to each other is sexual. "The administration does not want to know about it," Dr Vasseur writes. "There is no sex in prison, they say. Being deprived of freedom also means being deprived of pleasure. And yet sex is there, omnipresent."
Transvestite prisoners, many of whom have had breast implants or injected themselves with female hormones, are kept in a separate section to prevent their being raped. Some are forced by guards to perform sexual acts in exchange for food or access to showers. Three times Dr Vasseur was called in to care for young men, one a first-time prisoner aged 21, whose rectums were torn open when they were sodomised by cell-mates.
Dr Vasseur says the solitary confinement and disciplinary sections of the prison are an incitement to suicide. France has one of the highest prison-suicide rates in Europe - 124 French inmates killed themselves in 1999, including three at La Sante.
The men swallow razor blades, keys, coins and cutlery. They drink bleach and rat poison, but usually the only ones who succeed in dying are those who hang themselves.
Forty per cent of the prisoners at La Sante have not even stood trial. Nearly two-thirds are foreign, mostly black Africans and north African Arabs, and the majority of them are jailed for violating immigration laws.
La Sante's director, Mr Alain Jego, reacted angrily to what he called Dr Vasseur's "fallacious" book. He briefly opened the prison gate to 20 French journalists, but the strategy backfired when prison staff confirmed Dr Vasseur's allegations to reporters.
Mrs Guigou, the Justice Minister, now promises to build seven new prisons and restore five old ones, including La Sante. Dr Vasseur says the root problem is to redefine the purpose of incarceration. "Our prisons are designed to humiliate and break inmates, not reform them."