Slated to become the world's most populous country in the coming decades, Delhi has another problem to grapple with: being the world's most polluted city.

In 1910, Glacier National Park possessed 150 glaciers. Today, it's down to 25. The photos documenting these melting glaciers are absolutely stunning.

While some may perceive Iran as a country clinging to anachronisms, the astounding architecture of Tehran begs to differ.

Photography doesn't always present reality; it often manipulates it. Spirit photography is one of the earliest examples of that.

While the American economy seems to be on the rebound, the persistence of childhood homelessness complicates the "recovery" narrative.

When numbers drop in monarch migration, there's a problem. So what's going on?

Most think of sustainable design as a new phenomenon. In actuality, it's at least over a century old.

St. Augustine, Florida is the oldest continuously occupied European-founded city in the U. S., and it's diverse architecture tells of it's long history.

Just in time for spring, these rooftop gardens convene aesthetics, environmentalism and urban savvy into one stunning package.

Siberian craters have been popping up throughout the unseasonably warm region. What's causing it?

Copenhagen is the world's greenest city. Learn more about how they got there, and what the city is doing to combat climate change.