Photography might be banned in many museums, and historic sites, reason being the museum or historic site is exclusive, and has an admission fee, spoiling revenue for the museum/historic site, people will be like; "Oh, I've already seen that. It looks boring.", Or it may be disrespectful, such as if you are in a historic tomb, or for example, the preserved body of Soviet leader Lenin, it can disrespect the curators of the museum, and in a spiritual way, the body itself.