Ancient civilizations

From the air, lines of holes across Iran's deserts look like craters.

Ming-dynasty builders boiled sticky rice into a thin soup and mixed it into lime mortar.

These stone steps near Arles, in southern France, are what's left of the Barbegal mills: a Roman water-powered factory built around 120 to 130 AD.

More than half of the Colosseum's outer wall is missing, and it wasn't bombs or weather.

The Great Sphinx of Giza lost its nose long before Napoleon reached Egypt in 1798.

A painting in the tomb of Djehutihotep (El-Bersheh, Egypt, c.

When Mount Vesuvius erupted in AD 79, a building crew in Pompeii left a wall half-finished, with piles of raw materials still on site.

Those holes all over the Colosseum are not battle damage.

King Tut’s dagger was made from meteorite iron.

Pliny the Elder claimed Roman harbor concrete got "every day stronger" under the sea.

The Great Pyramid was built white: smooth, polished limestone from base to tip, and about eight metres taller than it is today.

Machu Picchu’s terraces hide an extensive drainage system.

Two miles from Stonehenge, around 2500 BC, people raised rings of timber posts now called Woodhenge, lined up on the midsummer sunrise like Stonehenge.

Ice in a desert summer had a winter supply chain.

Rust helped protect Delhi’s iron pillar for roughly 1,600 years.

Those rough blocks were never meant to be the Great Pyramid’s finished surface.

Rome's Pantheon, finished around 125 AD, still holds the record for the world's largest unreinforced concrete dome, nearly 1,900 years later.

A cold drink in Calcutta could contain ice shipped from another continent.

The ancient Greeks built the Diolkos, a paved stone trackway across the Isthmus of Corinth, and hauled ships overland on it for centuries; a canal across the Isthmus was attempted by Nero in AD 67 and not completed until 1893.

Honey essentially never spoils: its very low moisture, high acidity, and natural hydrogen peroxide make it inhospitable to microbes, and archaeologists have reported edible 3,000-year-old honey from ancient Egyptian tombs.

The ancient Romans used a concrete called opus caementicium that contained seawater and volcanic ash (pozzolana), and marine structures built with it have been found to be stronger after 2,000 years of seawater exposure than when they were first poured, because seawater triggers the continued growth of a rare mineral called tobermorite within the concrete.