The original church was built in 828 to house the body of St. Mark the Evangelist. His remains were stolen from Alexandria by two agents of the doge and, so the story goes, hidden in a barrel beneath layers of pickled pork to sneak them past Muslim guards. The escapade is depicted in the 13th-century mosaic above the front entrance door to the farthest left. This semicircular arch is the earliest mosaic on the heavily decorated facade; look closely and you'll see an image of the basilica as it appeared at that time.