This is 99% invisible. I'm Roman Mars.

The line to enter Barcelona's most famous cathedral often stretches around the block.

Lascagrada Familia, designed by Antony Galdi, draws so many people to see it that the neighborhood

is congested with tour buses and taxis and scooters. Some 3 million people went inside the church in 2016 and another 7

million came just to stare at the outside of this strange behemoth structure.

If you travel around Spain, you'll see a lot of old Gothic churches.

Producer Katie Mingle was in Spain earlier this year. But this one is different. First, it doesn't look

like a Gothic cathedral. It looks like it was built out of bones or sand or like it just

twirled out of the sea like a fractal. It looks organic somehow.

But there's another thing that sets it apart from your average old Gothic cathedral.

It isn't actually old.

Galdi wasn't able to build very much of it before he died in 1926.

Most of the church has been built in the last 40 years, and it still isn't finished.

Which means that architects have had to figure out, and still are figuring out,

how Gaudi wanted the church to be built. We are all together in a room, a special room,

the most important part of the building we are building.

That's Geronimo Bouchadio, one of the current architects of the building.

And he says the clues to understanding how to move forward on the construction of Las Akrada Familia

are kept in the room we're standing in right now in the basement of the church.

So since this is radio, can you describe what's in this room?

Ah, okay. How do you call this?

Shelfs.

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