World’s Great Walls Build on History : Shrines: Jerusalem’s Western Wall accepts prayers from all comers. China’s Great Wall invites visitors to walk atop it.

Most of the world’s most famous walls have outlived their original purposes of keeping people in or out.

Now they’ve found new life as tourist attractions, archeological sites and challenges to adventurers determined to “walk a wall.”

A pilgrim to the Old City of Jerusalem tries to wedge her written prayer into a crack between the ancient stones of the Western Wall, perhaps the most actively used wall today.

Even though she has folded the paper so many times that it is as small as her fingernail, she can’t find a crack along the women’s section of the wall that isn’t already stuffed with petitions.

She has to climb onto a chair and stretch as far as she can up the six-story-high wall to finally jam the paper among tufts of grass growing between the huge blocks.

Secreted inside is a prayer for two sick friends at home in the United States, more than 5,900 miles away.

“People come from all over and put their papers, their personal requests, into the cracks in the wall,” says Aharon Kellerman of the University of Haifa. “There is a special feeling of unification. It is the holiest place for Jews worldwide.” They believe that prayers placed in the wall ascend directly to God.

The western wall of the Temple Mount is all that remains of Roman King Herod’s magnificent structure, built after the destruction of Solomon’s Temple and itself destroyed in AD 70.

Today it is a place for swearing in Israeli soldiers, Memorial Day and Jerusalem Day ceremonies, bar mitzvahs and prayers during holy days and for rain during droughts. Periodically the tightly secured wall has become the backdrop for violent clashes between Arabs and Israelis.

A continent away, Hadrian’s Wall was built to separate the Romans from the barbarians in AD 122. It was the northernmost frontier of the Roman Empire, stretching more than 75 miles from sea to sea across northern England.

“It was Hadrian’s definitive, fortified border, controlling traffic and commerce. It is achieving much of those same ends today, but in different ways,” maritime archeologist Donald G. Shomette of Washington, D.C., said. Shomette has hiked the length of the wall and visited 22 archeological sites along the way.

The largest gathering of wall scholars meets every 10 years, touring what’s left of the structure. The 12th Hadrian’s Wall Pilgrimage will take place in 1999.

The world’s longest and most-visited wall--regarded as one of humankind’s grandest achievements--curls like a huge stone dragon across mountainous northern China, rising and falling, twisting and turning for nearly 2,000 miles.

The strategic importance of the Great Wall for defense against a succession of barbarian attackers caused dynasty after dynasty to expend money and manpower on its construction. In 214 BC, when existing state walls were linked in a continuous rampart at the command of Emperor Qin Shi Huangdi, at least 300,000 troops worked on the project.

Its elaborate reconstruction by the Ming Dynasty 1,600 years later is essentially the wall millions of tourists flock to today. “If a man fails to climb to the top of the wall,” a poem by the late Communist leader Mao Tse Tung says, “he is not a real man.”

In Moscow stands the Kremlin Wall. The 7,300-foot-long castellated brick structure was built as thick as 20 feet, with 20 fortified towers, as part of Ivan the Great’s grand plan in the 15th Century to put his stronghold in the top league of the world’s capitals. Today, though the Soviet government has splintered, the wall endures.

In sharp contrast, after 28 divisive years the infamous concrete Berlin Wall is being sold for souvenirs, auctioned for charity and ground into small pieces that will become the raw material for new roads. Two 330-foot sections are being preserved as monuments.