how, in a sense, megalomaniac that idea is. >> logan: gijs van hensbergen immersed himself in antoni gaudiii's life for ten years and wrote what's considered the definitive biography. he took us to see the nativity facccade, the only part built while gaudiii was alive. >> van hensbergen: it's the bible written in stone. >> logan: so, every single little thing that you look at there, every detail symbolizes something real? >> van hensbergen: yeah, and that was the idea, that we together would spend days here-- me teaching you, if i was a priest, what the story was, and what the symbolism was. and once you get inside is a wonderful, kind of spiritual >> logan: the ceiling is a striking display of gaudiii's engineering genius. he wanted the interior of his church to have the feel of a forest, because that's where he believed man could feel closest to god. and when you look upwards, you can see gaudiii's columns >> van hensbergen: trees are actually buildings, he said. it knows where to throw out a branch. and if you look at the sagrada famiiilia today, that's exactly what happens with those bizar