A museum is not a flea market. You must give an impression of unity and order. If you use a page background, the same one must be used for all pages. It must be very light and clear so that it does not interfere with readability of the text. Avoid backgrounds with large repetitive graphics even if they are related to the subject .
Easy navigation is one of the keys to a successful site.
A web site usually consists of a number of pages through which the reader must find his way. But a website is not a book starting with page 1 and ending with page 20. This system is fine if the page just fills the screen space, but less satisfactory if the page needs some scrolling which is the general case. The rest of the screen will be the main window where all the pages will appear. So the reader will be able to jump to any page immediately and easily.