They were consistently dug as limestone quarries and by the 18th century, the caving in of some of these quarries posed safety threats, so the government ordered reinforcing of the existing quarries and dug new observation tunnels in order to monitor and map the whole place.

Most of the quarries have closed.

Here's a piece of limestone.

You guys still go swimming in the quarries?

Limestone pie and hot melted silver.

Parks old quarries that they were transformed into parks.

Those white cliffs are a dense Cambrian limestone.

Would it give this block of limestone new properties?

And it's just limestone, nothing really special about it.

The core comes up as these cylindrical tubes of limestone.

And it's different than this limestone, you can see that.

Quarries once made the nature, and sometimes we took this and we transformed.

And that's not snow that's what the white limestone looks like.

Now a block of limestone, in itself, isn't particularly that interesting.

We don't just want limestone dumped everywhere in all the pretty canals.

So the bones were moved from the cemeteries into the quarries, making them into the catacombs.

And Lost City was characterized by these incredible limestone formations and upside down pools.

The dip slopes in the overlying limestone, the orientation of the flora, shallow waters...

There are huge walls buried under limestone plateau in the northeast of the Great Pyramid of Khufu.

And so here the protocells are depositing their limestone very specifically, around the foundations of Venice, effectively petrifying it.

But gradually, as the buildings are repaired, we will see the accretion of a limestone reef beneath the city.

But imagine what the properties of this limestone block might be if the surfaces were actually in conversation with the atmosphere.

It was Crease Limestone, and that was produced by sea creatures 350 million years ago in a nice, warm, sunny atmosphere.

This first of the two strategies is like a hunter, exploring a forest in search of a particular quarry, who finds other quarries along the way.

I might have got good limestone within a mile or two and burned it myself, if I had cared to do so.

I'd like to be able to stroll through the campus and look at the limestone, but I just feel out of place.

According to the Roman scholar Pliny the Elder, citizens of the Empire believed that limestone from a quarry near Troy would dissolve flesh.

So, all the ideas about how to transform through design old quarries and open universities and botanic garden all of it's related to how we teach the children.

And if you look even closer, you'll see, in that limestone, there are little shells and little skeletons that are piled upon each other.

This is our protocell technology, effectively making a shell, like its limestone forefathers, and depositing it in a very complex environment, against natural materials.

The Workshop will connect people with passion in the community with organizations and people with assets that can accommodate renewable generation projects municipal buildings, hospitals, brownfield sites, used landfills, quarries, business rooftops.

And architect Christian Kerrigan has come up with a series of designs that show us how it may be possible to actually grow a limestone reef underneath the city.

I love how they were able to preserve most in everything that makes you feel close to nature butterflies, man made forests, limestone caves and hey, even a huge python.

You put the stick in the powder to take the sacred ashes well, they're not ashes, they're burnt limestone to empower the coca leaf, to change the pH of the mouth to facilitate the absorption of cocaine hydrochloride.

Nelson Mandela I take a little piece of limestone from Robben Island Prison, where he labored for 27 years, and came out with so little bitterness, he could lead his people from the horror of apartheid without a bloodbath.

If you walk around the city of Oxford, where we are today, and have a look at the brickwork, which I've enjoyed doing in the last couple of days, you'll actually see that a lot of it is made of limestone.

Rather than having a B movie origin, however, its roots can be traced back to the early Roman Empire where the Greek word sarkophagus was used to describe the limestone that a coffin was made of, not the coffin itself.

But it goes a mile and a half in a straight line, due east into the range, into very interesting territory except that, as you'll see when we go inside in a minute, we were hoping for limestone but in there is just shale.