The Marble Mountains in Vietnam are a cluster of five hills made of marble and limestone, named after the five elements. They're like nature's own rock sculptures with cave entrances and tunnels to explore. You can even climb to the top for a killer view! Plus, there are Buddhist and Hindu grottoes nestled within, adding a spiritual vibe to this tourist hotspot. It's also known for stone sculpture making, so you might spot some cool crafts while you're there. Just watch out for the stairs – there are 156 of them to conquer if you want that epic panoramic shot!