S1 E2 | Cathedral Catastrophe

It's an 800-year-old icon, an irreplaceable treasure, with a state-of-the-art smoke detector; how did Notre Dame cathedral catch fire? We go up them and down them, sometimes we fall down them; no one thinks about stairs until they make us; is using our feet all in our heads? Giant smokestacks push our junk into the sky, but when they become junk themselves, they get blown to bits; when the earth quakes, even the biggest structures can fail; is there such a thing as an earthquake-proof building?