In ancient Pompeii, residents repaired roads with molten metal.

Once again, history surprises us with its so-called "backward past". One of the new discoveries made in Pompeii are the so-called metal roads.

When the stone pavement of the road cracked, Roman craftsmen filled the cracks with molten metal. This method not only restored the road but also strengthened the city.

However, in order to melt iron or iron-containing slag, a temperature of about 1600 degrees Celsius is required. But it's one thing to melt the metal, and quite another to transport it to the repair site. How the Pompeians transported the liquid iron remains a mystery.