Hexham Abbey

pdf documents.. 

Portable Document Format (PDF) is a file format developed by Adobe Systems for representing documents in a manner that is independent of the original application software, hardware, and operating system used to create those documents. A PDF file can describe documents containing any combination of text, graphics, and images in a device independent and resolution independent format. These documents can be one page or thousands of pages, very simple or extremely complex with a rich use of fonts, graphics, colour, and images.
(From Wikipedia)

How can I read a pdf document?...

Using a reader. There are various free readers:
Adobe Acrobat (pukka, but a large download..35mB)
Foxit (quick & easy - about 5mB)