Visitors to the Vatican are getting a heads-up that nothing is eternal -- at least when it comes to the Holy See's museums. Admission prices just went up by a euro to 13 euros, and opening hours have shrunk for visitors not affiliated with organized tour groups.

Until very recently, doors opened at 8:45 a.m. Under the new rules, which went into effect last month, Vatican-approved tour groups with reservations will still be able to get in at that early hour, but individual visitors must wait until 10 a.m.

Vatican officials say the shorter hours are part of a plan to control overcrowding by phasing in a mandatory reservation system over the next year for all visitors, whether they are on a group tour or not. Tour groups are being given priority now, they say, because they are easier to manage.

But some in the Italian tourism industry say that when you add the time waiting in line -- which can be two hours or longer in the summer -- and the fact that tickets are sold only until 12:30 p.m. in the off season and 3:30 p.m. in high season, visitors not part of a group may have barely enough time to see anything at all.

And of course there is much to see: Michelangelo's Sistine Chapel, for instance, and the rooms Raphael painted for Pope Julius II. These treasures of Western art are, for many tourists, a principal reason to visit Rome in the first place.

But the number of visitors to the Vatican has nearly doubled in the last 10 years, hitting a high of 4.2 million in 2006, and has resulted in the overcrowding of a structure originally built to accommodate a Renaissance papal court, not up to 20,000 visitors at a time shuffling around one another.

Between enormous tour groups and rowdy school-trippers, a visit to the Vatican Museums can become "more of a traumatic than an artistic experience for tourists," said Paola, one of several guides who were interviewed and who asked that their full names not be used for fear of offending the Vatican.

The changes come as many Italian cultural sites take measures to control overcrowding.

Before a booking system went into effect at the Uffizi Gallery in Florence, the lines at the entrance rivalled those at the Vatican. While the Uffizi caps at 900 the number of visitors who can be inside at one time, some 1.5 million visitors managed to tour the galleries last year. Once a major restructuring project is completed in four or five years, the number of people allowed in at one time is expected to increase significantly.

The Colosseum, too, has a booking service, but because all visitors have to pass through security checkpoints, with 3.9 million visitors a year, lines are inevitable. "It's still pretty fast," said Rossella Rea, the archeologist in charge of the monument.

But it could be faster, so a new entrance point is being developed at the eastern end of the Colosseum. If financing allows, a now-closed section of the main floor's walkway will be restored this year, so visitors will have more space to spread out. Granted, the Roman amphitheatre is large (it once held 80,000 ancient Romans), but tour groups still manage to trip over one another.

But at the Vatican, critics worry that the shorter hours will lengthen the lines, which on some days reach nearly a kilometre around Vatican City's walls to the colonnade of St. Peter's Square. Now, people will still line up, but "they won't have the certainty that they'll get in before the museums close," said one American guide who asked not to be named.

Still, something must be done about the overcrowding, said Francesco Buranelli, the director of the Vatican Museums.

"The snaking line is under everyone's eyes; it's jaw-dropping, even though it does move pretty fast," he said, notwithstanding the increased security measures at the entrance after Sept. 11, 2001.

The new hours, he said, were the first step toward the mandatory reservation system that will go into effect in January and that museum officials said will allow them to spread out visitors during the day. For now, favouring tour operators, who bring in more than a third of total visitors, is seen as a "convenient choice to help the museums through this transition," Buranelli said.

Unlike many other cultural institutions, the Vatican Museums were among the first museums to have audio guides, and a restaurant has operated within its walls since 1975.

It has also been selling guidebooks and monographs on its collections for some 20 years, recently branching out into new lines, like the high-end Vatican Library Collection, which includes merchandise like reproductions of documents from the Vatican's archives and facsimiles of papal seals.