You’ve been tasked with rebuilding a crumbling wall, but rather than working with stones or bricks, your job is to stack bones—femurs, tibias, and skulls—atop one another. That was the case for the masons (craftspeople who work with stone, brick, or concrete) who spent last year restoring the Catacombs of Paris. They were part of a broader team of curators, architects, designers, and technicians who carefully brought this dwelling of the dead back to life.