A short video showing inspectors inside the Duomo in Florence

It is so easy to lose any sense of scale when looking up into that dome. Seeing a worker hanging there in a harness drives home just how huge it really is AND what a miracle of engineering it was that Brunelleschi pulled off.

Not a video, but this excerpt from Mark Twain's "The Innocents Abroad" relates his experience in St. Peter's in Rome as he viewed workers suspended from the dome over the main altar:

"To stand in the door of St. Peter’s and look at men down toward its further extremity, two blocks away, has a diminishing effect on them; surrounded by the prodigious pictures and statues, and lost in the vast spaces, they look very much smaller than they would if they stood two blocks away in the open air. I “averaged” a man as he passed me and watched him as he drifted far down by the baldacchino and beyond--watched him dwindle to an insignificant school-boy, and then, in the midst of the silent throng of human pigmies gliding about him, I lost him. The church had lately been decorated, on the occasion of a great ceremony in honor of St. Peter, and men were engaged, now, in removing the flowers and gilt paper from the walls and pillars. As no ladders could reach the great heights, the men swung themselves down from balustrades and the capitals of pilasters by ropes, to do this work. The upper gallery which encircles the inner sweep of the dome is two hundred and forty feet above the floor of the church--very few steeples in America could reach up to it. Visitors always go up there to look down into the church because one gets the best idea of some of the heights and distances from that point. While we stood on the floor one of the workmen swung loose from that gallery at the end of a long rope. I had not supposed, before, that a man could look so much like a spider. He was insignificant in size, and his rope seemed only a thread. Seeing that he took up so little space, I could believe the story, then, that ten thousand troops went to St. Peter’s, once, to hear mass, and their commanding officer came afterward, and not finding them, supposed they had not yet arrived. But they were in the church, nevertheless--they were in one of the transepts. Nearly fifty thousand persons assembled in St. Peter’s to hear the publishing of the dogma of the Immaculate Conception. It is estimated that the floor of the church affords standing room for--for a large number of people; I have forgotten the exact figures. But it is no matter--it is near enough."

Thank you for that image, Mr. Clemens.