You're listening to the documentary in the studio from the BBC World Service.

I'm Julian May and this week we're revisiting the Argentinian artist Thomas Saraceno.

We're in what used to be East Berlin and his studio, a large red brick building, used to be a factory.

It's covered in very colourful graffiti.

The windows are barred and beyond a heavy metal door

is the space where Thomas creates the spider webworks,

airborne sculptures and installations he exhibits all over the world.

This building has its place in art history.

This was the factory where the film company Agfa developed colour photography.

Now, that was good for art, but not for the environment.

The chemicals they brewed up and stored here ruined the soil.

They asked me, don't cultivate potatoes or apple trees or something, because besides not

knowing the colors that the apple might come also might be poison. It's kind of quite paradoxical.

You know, the guys who have invented a record of how an apple should look like which color should have,

they have paused the lounge for now and maybe come up with a new color,

which is out of the canons of what it should look like, a color of an apple.

You have two big buildings here.

When you came here, were they derelict?

Yeah, I kind of protected in the building.

But yeah, they were completely...

I think nobody was in the building for more than 25 years or something like that.

There were a lot of pigeons and other animals and spiders.

...