What it is: It's a path that's nailed to the sides of a narrow gorge in El Chorro, in the province of Málaga, Spain. What makes it brutal: To give you an idea, this is known as "The World's Most Dangerous Walkway" and was just re-opened after renovations to make it slightly less precarious. Still, these steel planks hang 100 feet in the air and the best part is, some of the sections are missing. Isn't that exciting?!