Stretching 300 miles and standing over 700 feet tall, the vast, icy divider known simply as "The Wall" in Game of Thrones is one of the most intimidating structures in literature. During a recent visit to Northwestern University to receive the Medill Hall of Achievement award, author George R.R. Martin revealed that he was inspired to create the daunting barrier after experiencing a harsh winter in Chicago.

"The coldest winter was in Chicago," Martin said of his freshman year at the Medill School of Journalism. It was the Chicago Blizzard of 1967, the largest single snowfall in the city's history. "There was so much snow that winter, you couldn't see, all snow, all ice, and it was so very cold," Martin recalled, comparing the blizzard to being in the trenches of World War I. "I remember walking through the trenches and the tunnels of ice, the wind blowing so you couldn't even see. It's an experience that never left me."

According to Nerdist, Martin has also said that a wall built during the Roman Empire, Hadrian's Wall, inspired the landmark in his novels. As for the structure that appears in the HBO series, supervising art director Paul Inglis says in a behind-the-scenes video (below) that the quarry used as the build location helped shaped what The Wall from the books would look like on screen.