Meanwhile, ancient Roman concrete is still standing strong after thousands of years, and not only does it resist damage, but the salt water actually makes it stronger. X-ray examinations have found the key to the mixture's incredible longevity, which could help improve modern recipes.

In recent years, we've electrified concrete to melt snow, made it more fire-resistant, added bacteria to make it self-heal any cracks that form, and have found ways to "program" it to be stronger. But it seems that the Romans were way ahead of their time, with a superior method for making concrete that could stand the test of time.

Although the complete recipe has been lost over the millennia, studies of samples have shown that volcanic ash, lime and seawater are the main ingredients.