While many cities and villages along the Indian Ocean suffered catastrophic losses from the December 2004 tsunami, the port city of Pondicherry, India, and its 300,000 inhabitants were spared. Just beyond city limits, 600 people were killed by the devastating tidal wave, but Pondicherry withstood the tsunami. Why were they protected ?

The answer began 250 years ago when France colonized the city. The French built a massive stone seawall. Year after year, the French continued to strengthen the wall, piling huge boulders along its 1.25-mile length.

The French stopped building Pondicherry's seawall in 1957, but their work prepared them for a disaster that would occur five decades into the future.