14. Iron Pillar of Delhi
The Iron Pillar of Delhi is something utterly tremendous in the field of ancient metallurgy â€” it's almost pure iron, yet has sat in the open air and weather for 1600 years almost without corrosion. By now it should be a mass of rust and rubble, but instead it stands tall, all 7 meters and six tons of it. The reason it lasted so long? Well, it's a dense and scientific explanation, but let's call it a combination of excellent ancient skills, a unique set of impurities in the iron, and the conditions around it. I'm sure there are plenty of people who would love to figure out an easy way to stop their metal from rusting.