Hello and welcome to Mysteries of Science. My name's Stevie and I'm the deputy editor of Science in Nature,

the monthly magazine from the team behind the Week Junior. And I'm Michael, the junior editor. On this

podcast, we take a look at our favourite mysteries of science. These are the strange phenomena

and bizarre events and have left scientists scratching their heads and despite their best efforts

remain well and truly unsolved.

So tell us, Michael, where are you off to you today?

Well, for this podcast, we're going high up into the Peruvian Andes in South America,

more than 2,000 metres above sea level to the ancient lost city of Machu Picchu.

Machu Picchu. Now, I've heard that name before. So what's so special about it?

Machu Picchu is one of the world's most spectacular places. In fact, it was actually named one of the

seven wonders of the modern world back in 2007. But it's also one of the most mysterious. Who really

built this autumn citadel and what they used it for is something that has puzzled people for a long

time.

Oh, I've heard lots of crazy theories about this place, including one, that it said was built by aliens?

Well, let's take a trip to Peru and find some experts who can tell us the truth about this

secret city in the sky. This is Mysteries of Science.

So, Michael, our mission today is to investigate who built Machu Picchu, how they did it and what it was used for. I think we need to start with a quick history lesson.

Machi Picchu is said to be in Incan city. Who were the Inca's?

Well, thankfully, we've got a few experts here to explain it to us.

I'm Kim McCorrie, and I am a writer, filmmaker, and anthropologist.

Kim has written four books about Peru and lived in the country for five years.

Here he tells us a little bit about who the Inca's were.

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