Uncovering The Mystery Of The Great Wall

You would think the crowds, or using the Great Wall as a stage, or turning the Mongol invasion into a souvenir moment, or even the cable cars for ever more tourists, would most annoy American David Spindler.

But his greatest fear is losing the Great Wall by losing its history, CBS News correspondent Barry Petersen reports.

"Well, right now there are no single academics anywhere in the world, including China, whose major focus is the Great Wall," Spindler said.

So he may be the only person who's life is all about the Great Wall, making what money he can from being a tour guide.

Teaching himself Chinese to read original Ming Dynasty records on construction, fascinated by a history that Chinese scholars consider a waste of time.

Making solitary hikes to create a massive computer database, and sometimes meeting up with the past.

"In the middle of the night I heard the sounds of metal on stone," he said. "Certainly nobody around, so my hypothesis is that it was a ghost."

There are a lot of amazing things known about the Great Wall, but the most Great Wall there is, because its several walls built over the centuries crisscrossing China - even satellites can't see it all.

"There are sections of wall that are just little stones along the side of bridges," Spindler said. "You have to get down with the brush and look very closely at it."

And half the 4,000 miles of wall may already be gone. Some destroyed by Mao who wanted to erase the past. Some, like a tower in the 1930s, simply lost by neglect.

Spindler believes he can save at least the legacy of the Great Wall - the only man in the world creating a modern-day record not just of stones, but the stories they have to tell.