Ta Prohm of Angkor in Cambodia, former heart of the Khmer Empire

Angkor of Cambodia was the heart of the Khmer Empire for about 550 years (9th to 15th centuries) before overpopulation and environmental degradation lead to its abandonment. At its peak, the city spawled over an area the size of Los Angeles and supported more than a million people. The picture above shows Ta Prohm, a buddhist monastic complex where some of the original vegetation has been left uncleared by archaeologists.

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Sunset over the Caribbean off the Yucatan Peninsula in Mexico

Sunset over the Caribbean Sea off the Yucatan Peninsula in Mexico. The 80-mile stretch of coastline south of Cancun on the Yucatan Peninsula of Mexico -- now called the Riviera Maya -- has undergone a remarkable transformation over the past decade, becoming Mexico's fastest-growing resort area. Places like Playa de Carmen and Tulum have gone from small towns to booming resort developments as developers bypass bureaucratic approvals to buy and build up beachfront lands as fast as possible. Mangrove swamps, which are largely responsible for the region's sparkling clear waters and biologically rich coral reefs, are the primary victims of land clearing for hotels and condominiums.

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The Routeburn track of the southern island of New Zealand is considered one of the most beautiful hikes on the planet. Ths hike generally takes 2-4 days depending on side trips, conditions, and level of fitness.

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