Okay, so we 're going for a ride around the pyramids.

The Great Pyramid was the tallest man - made structure for nearly 4, 000 years, only surpassed by a large margin by the Eiffel Tower in 1889.

147 meters high.

You are interested by climbing? – Yeah. Let's climb it!

But it's not free. – How much?

What makes the pyramids even more impressive is that these structures were built over 4, 500 years ago when Egyptians didn't have wheels or steel.

The only metal available was copper and copper alloys.

It took about 2 million stones to build that pyramid.

Well, I call them stones. Giant rocks.

Somewhere between one and a half to three tons each.

The pyramids took about 20 to 30 years to make.

It's a long time,

but if you think about the number of stones, a couple million stones in every pyramid, you would have to be laying a stone roughly once every three minutes,

if you consider a regular work day like a 10 hour - 12 hour work day.

Nobody knows how they built it. It's still secret.

But a lot of people just try to do their best to give you some information about how they did it.

But we must say it's secret.

They did and they take the secret with them. Nobody knows.

No plans survived to show us how the pyramids were built.

So perhaps it's not surprising that this is the subject of countless conspiracy theories, involving aliens, time travel or lost technologies.

But there is a less farfetched myth, which has become widely accepted that the pyramids were built by slaves.

But recent discoveries suggest the pyramid builders were not slaves at all.

They were skilled workers.

Well preserved tombs near the pyramids suggest that their hard labor and sacrifice were rewarded.

If these workers had been slaves, they would not have received such honorable burials.