Do Take pictures (where allowed). Leaving your imprint on a place and taking bits of it home with you are both frowned upon, but that doesn't mean you can't have any remembrance of your journey. 'Take only pictures, leave only footprints' is generally a good rule to follow, especially with objects that have been around for thousands, or millions of years. But there are certainly exceptions. Several locales have banned selfie sticks, and you should always follow the rules of a particular site.