Ever seen a city floating above the clouds? That’s Machu Picchu. Terraces climb the mountains like giant green staircases, and stone temples peek through the mist. Built by the Incas without a single ...

I first set foot in the Pyrenees in 2006. Two years later, I began a large-scale survey of mountain lakes and amphibian populations: from east to west, I covered more than 100 mountain lakes located ...