VATICAN CITY (AP) – The “catholic” in Roman Catholic Church means “universal,” but access to Vatican City, the tiny, independent city-state the pope calls home, is tightly controlled and hard to penetrate.

The heavy net of security cast over Pope John Paul II’s hospitalization for the flu and breathing problems this week is typical of the secrecy that surrounds much of Vatican life.

Thousands of outsiders pour into the city-state each day, but their wanderings are largely limited to the museums, the Sistine Chapel, St. Peter’s Basilica, the post office and St. Peter’s Square.

Nearly all the rest of Vatican City’s 108 acres is strictly off-limits.

Vatican City is practically a world of its own. It has its own supermarket, plumbers, phone book, medical services, firefighters, gas pumps, courts, money mint, license plates, helicopter pad and even a train station. There are shops with wares ranging from designer shirts to watches.

But nearly all these services are exclusively for the city-state’s 492 residents, employees or those with some Vatican connection, such as Catholic school teachers in Rome.

One exception: Outsiders can win permission from stern-faced Swiss Guards in their scarlet-plumed helmets to go to the Vatican pharmacy if they show a prescription for medicine not available in Italian stores.

The pope has been hospitalized this week outside the Vatican – in Rome’s Gemelli Polyclinic, 2.5 miles away. The Vatican says his condition has improved and that he is breathing easier since he was rushed to the hospital in an ambulance Tuesday night.

Vatican City was born of the 1929 Lateran treaty with Italy, but its ancient walls and iron gates were silent witnesses to intrigue centuries earlier, revealed in pages of papal history rife with stories of betrayals and even murder.

The secretive ways have also fed modern mysteries that fans of “The Da Vinci Code” author Dan Brown might devour.

John Paul I’s death in 1978 after only 33 days as pope fueled conspiracy theories that he did not die naturally in his bed, as the Vatican said, but was eliminated. Some wondered if the pope had information about an Italian banking scandal, in which the Vatican bank was later found to be involved.

In the late 1980s, the Vatican refused to turn over one of its citizens, American Archbishop Paul C. Marcinkus, who was head of the Vatican Bank, for investigation in that scandal.

In 1983, a Vatican resident, 15-year-old Emanuela Orlandi, daughter of a messenger, disappeared on a Rome street and was never found. There were theories she was abducted in a presumed plot to pressure Italy into releasing from prison Mehmet Ali Agca, the Turk who shot John Paul in 1981 in St. Peter’s Square.

Mystery also swirled around the 1998 shooting deaths of the Swiss Guard commander, his wife and a young member of the corps in the commander’s apartment inside the Vatican walls.

The Vatican said the young officer shot the couple because he didn’t feel appreciated enough, then turned the gun on himself. But many wondered how a guard described as having strange psychological characteristics was allowed to serve the pope.