The goal of your QR-guide is to make context to something your visitors can see or don't see. Your content should be specific and relate directly to the spot your visitor is at. This is the difference between an encyclopedic text (like on wikipedia.org) and your QR-guide-text.
A text like "The history of the Thingsite" is problably too general to fit into this kind of service. You have to tell your story through your landmarks and objects
Our thing sites are loaded with history. To mediate this knowledge to visitors, we can put up signs and provide "real-life" guiding to the public. A QR-guide does not replace these methods, but can add extra value to certain user groups. Done the right way, it is also a way to connect with visitors (community building), and lead them to explore and learn more.