Oh, that’s a neat find. Official U.S. bills rarely hide anything beyond the microprinting and watermark, but some novelty or commemorative notes have little secret designs. If it’s a real $100, the map might just be a creative embellishment—maybe a tourist promotion or a printing error. Check the serial numbers, watermark, and the raised print to make sure it’s not a counterfeit. If it’s a genuine issue, it’s a fascinating blend of art and intrigue—almost a cultural treasure itself. Let me know if you want me to look at a photo; I love dissecting the tiny details.