Is it an image of X?
First, you want to make sure you found a real image of X place. If you search Google for images, you're not only seeing images from museums or institutions, but from everyone putting photos up online. While it is very possible to create completely fake images, I think it more likely that you'll run into ones where they were simply mislabeled out of ignorance, rather than malice.
Be picky! Use ones from institutions affiliated with the site, or educational institutions such as museums or libraries, or well-respected media organizations.
If you can't determine who is responsible for the image, don't use it.
If you have any doubt as to the authenticity of the image, double-check it.