A look at 15 of the world's largest organisms, from whales to bears and elephants; even trees are included.

A look at some of nature's most intelligent, social, and organized animals - ones that might seem more human than human in some ways.

Some historic structures, like Angkor Wat in Cambodia or the pyramids in Egypt, draw hundreds of thousands of tourists. Others have been reclaimed by nature.

Landfills don't have to remain steaming heaps of smelly rubbish. Take these ten former trash heaps that are now characterized by abundant green and diverse wildlife.

A look at stunning temples and monuments built into massive, natural caves.

A look at ten of the world's most beautiful caves.

Renewable energy power plants are usually upgraded before they fall into disrepair. Yet sometimes relics of a renewable past are left scattered across the landscape.

Fascinating man-made islands and floating communities including a former fort fit for a Bond villain and a picturesque Pacific garbage dump.

These animals, whether they were invited, invading, or simply curious, have found their way, unexpectedly, into urban areas.

Inspirational globes for Earth Day inspire a sense of unity and invokes the urgency for everyone to get on board with the green movement.

Cars are great, but have you ever wanted to get rid of yours? There are cities out there where it is possible to get by and get around without getting into a car.

From a Mayan treehouse playground of the rich to the home of descendants of Bounty mutineers, here are 10 mysterious and unusual islands.

The world currently has 121 gigawatts of installed wind power. But not all wind farms were created equally.

These 12 visionary films create dismal futures caused by present-day problems like global warming, wildlife extinctions and resource depletion.

Going off-the-grid often means traveling to somewhere remote, but it doesn't have to. Cutting-edge constructions mean that unplugged, self-sufficient sites can be found both in the city and in the countryside