Legend has it that when the Charles Bridge was built in the 14th century, farmers supplied raw eggs to strengthen the mortar. One village's peasants, fearing breakage along the way, boiled the eggs first -- and are still laughed at today.

Some believe the much-loved story reflects reality, while others think it grew from a nation's pride in the medieval bridge's endurance. Either way, the Charles Bridge has long stood at the heart of Prague's identity. It is one of Central Europe's premier tourist attractions. And now -- eggs or no eggs -- it needs repair.

While the graceful pedestrian bridge lined with statues is just one of thousands of historic structures in the Czech Republic that badly need maintenance or restoration, it is probably the most important. Yet the required work has been stymied for more than a decade by bitter technical disputes between experts and concerned citizens.

"It's heritage, number one. It's not just a bridge," said the city's previous mayor, Jan Kasl, who until leaving office last year pushed hard but unsuccessfully to begin protective work. Responsibility for the bridge lies primarily with the city government.

Charles IV laid the bridge's foundation stone at an astrologically auspicious moment in 1357, and the structure was completed around 1400. It has gone through repeated damage and repair since then.

"When I come here I feel like I'm in paradise," said Vladimir Pinta, 69, a saxophone player who works the bridge, which offers a spectacular view of Prague, including the fairy-tale hilltop castle and the picturesque roofs of the city's Old Town.

"Prague wouldn't be Prague without the bridge," said Eva Imrichova, 30, a Czech visiting the capital. "It has atmosphere. It's beautiful. There's a mood to it."

The 1,600-foot-long bridge over the Vltava River looks old, but charmingly so. It combines beauty and history in a way that makes it "natural for every Czech to be proud," said Jana Cisarovska, 26, who sells etchings on the bridge. "An American woman came by and said, 'It's just like something out of Disneyland.' "

But beneath the cobblestones, trouble is brewing. In the 1950s and 1960s, cars were allowed on the bridge, and salt was spread during icy winters. Largely because of that salt, the bridge's interior is waterlogged; biological and chemical processes are eating the sandstone from inside out.

The stones of the bridge "are getting soft -- they are much more porous than they used to be," said Jiri Witzany, rector of Czech Technical University in Prague and part of a team that has spent years refining a conservation plan, only to be repeatedly blocked by critics' complaints. The water-filled pores make "an excellent environment for bacteria," which produce chemicals that eat more of the stone, he said.

Restoration cannot make the stones strong again, but it can stop the rapid weakening. So the longer the delay, the worse shape the bridge will be in after the repairs and the shorter the probable life span, Witzany said. If properly cared for, the bridge should be able to survive for centuries, he said.

"I love Charles Bridge," Witzany added. "The construction, which has within it a tremendous message of the advanced level of medieval craft and the natural connection of the function and purpose; the simplicity of the shape, with its aesthetic and creative impact. When I compare it with some of the decadent creations of modern architecture . . . then I admire the bridge even more."

The statues lining the bridge were added starting in 1683, when the Jesuits put up the bronze image of St. John of Nepomuk. A relief at the base of that statue recalls his 1393 execution: He was thrown off the Charles Bridge in a suit of armor. According to the story depicted there, he was killed for refusing to divulge to King Wenceslaus IV the confessions of the queen, although historians say he was really the victim of a bitter church-state conflict.

Several of the original statues have been moved to museums for safekeeping, with copies replacing them on the bridge.

Witzany's group -- it includes bridge construction experts, an architectural design studio and technical researchers -- has largely focused on the processes destroying the stones from within. There are also worries about the strength of the bridge pillars' foundations in the riverbed and the effects on the stonework of repeated freezing and thawing of water that gets into cracks.

Part of the dispute between the technical group and its critics is over the relative importance of these various threats. While the bridge survived a severe flood last summer without visible damage, fears remain that a similar onslaught in the future could cause serious harm.

Critics centered in the Club for Old Prague, a preservation group, want priority given to strengthening the foundations, and work on the bridge surface limited to little more than a new layer of waterproofing not far beneath the cobblestones.

Club members have fought to retain a steel-reinforced concrete plate running the length of the bridge that was installed 20 inches beneath the surface during the last major renovation in the 1970s. They argue that it proved of value in the recent flooding and that removing it could destabilize the arches.

Milan Pavlik, deputy chairman of the club, said that during the August flood there was a moment when the bridge began to sway. Heavy machinery, which had been moved onto the bridge to break up concentrations of debris caught against its pillars, was quickly removed. Pavlik said he believed the plate helped the bridge escape any noticeable harm.

The technical group has proposed removing the concrete plate as a useless addition to the historic structure. It wants to put the waterproofing layer deeper under the surface, then install drainage-and-ventilation pipes through holes cut into the bridge's arches.

Arguments over issues such as these have blocked repairs for about 15 years.

While those fighting over what to do generally agree that work on the bridge is needed, among the public there are still skeptics who think the bridge is in fine shape.

"I don't think it's all that necessary," said Cisarovska, the etchings saleswoman. "It's a struggle for money. Whoever gets the order for the repair will make a lot of money on it."

The last time the bridge suffered major damage was in the great flood of 1890, when some arches collapsed, Witzany said. Work to strengthen the pillars' foundations after that disaster saved the bridge in last year's flood, he said.

"The repair of the bridge took place within a year," he added. "Probably there wasn't as much discussion."

The Charles Bridge in Prague, completed around 1400, is deteriorating from within, but repairs have been stymied by disputes between experts and citizens.