A massive wall of ice protects the Seven Kingdoms from the dangers of the wintry north in HBO’s hit series Game of Thrones. But in the real world, an ice structure standing at half the height of the Empire State Building would face more problems from physics than any wildlings or White Walkers lurking in the lands Beyond the Wall.

The mighty Wall has little to fear from science in the medieval fantasy world of Game of Thrones — human hands got some help from magic to build the icy barrier up to its massive height of 700 feet across a distance of 300 miles. A similar touch of magic would be needed to keep the Wall standing in real life, scientists say. Otherwise gravity’s irresistible force would eventually bring it down.

“Even at very cold temperatures, large ice masses deform under their own weight,” said Dartmouth engineering professor Mary Albert, Executive Director of the U.S. Ice Drilling Program Office. “And over long time scales, ice flows, so it would not hold its original shape for thousands of years.”

The idea for the fantastical fortification came to George R.R. Martin, author of the A Song of Ice and Fire books that inspired the HBO TV show, when he stood on Hadrian’s Wall, which was built by the Roman Empire. Martin envisioned his much bigger Wall as a towering defensive structure that would dwarf real-life versions such as Hadrian’s Wall (15 feet tall) and the Great Wall of China (30 feet tall).

Only Mother Nature has built real-life ice structures rivaling the Wall, such as the Greenland and Antarctic Ice Sheets, which are several miles thick. Such ice structures formed over “hundreds of thousands of years of snow falling in very cold locations where there is not melt,” Albert said.

Image courtesy of HBO