And if you thought Matthew was thrilled to see the dome from the outside, just imagine how he felt walking through it. A staircase sandwiched between the dome’s inner and outer shell lets you see how Brunelleschi built his masterpiece. Skeletal stone ribs provide the octagonal shape and transfer the weight of the bricks, which are locked in place via a herringbone pattern. Matthew kept running his hands over the brick and saying, “Imagine, Brunelleschi himself probably touched these walls.” (Yeah, as well as billions of tourists — time for a little hand sanitizer.)