Here’s a mosaic of some saint or other, from St. Mark’s Basilica in Venice. He was very high up in the church, on the inside of a dome I think, and I had to crank up the telephoto to capture him. The tesserae are in pretty good shape.
Though St. Mark’s is the iconic church in Venice, it’s a basilica, not a cathedral. The actual cathedral is another big church on another island, and I never got around to visiting it.
Though I don’t know which saint this might be, we can easily see him as St. Nicholas, making him a welcome visitor in the holiday season.