Being afraid of heights might be the single most common fear aside from a terror of spiders. Even if you don't consider yourself scared of high places, it's hard not to feel a chill race up your spine when you look down from the top floor of a tall building. But there are people who aren't afraid to brave heights – some for fun and others for work. Some spend every day of their life high in the sky putting together skyscraper after skyscraper, while others chase the thrill of climbing mountains – and it was all much more precarious in the past. These historical photos of people relaxing or working in high places might just trigger your fear of heights, even from your first-floor apartment.