This is a huge, wonderful reference book on almost every aspect of art you can think of. Beware, though, this is not a "picture" book nor is it a narrative history of art. Though it does contain about 50 color paintings between its covers, it is basically an art encyclopedia with entries laid out in alphabetical order.
Besides containing biographical information on just about every artist who ever took brush in hand it has entries on major museums, schools of art, and various other feature length articles on:
Classicism
Casting
Conservation and Restoration
Illuminated Manuscripts
Gilding
Funerary Monuments
Gothic Art
Arts of Countries
Portraiture
Proportion
Impressionism
Perspective.
That's just a sampling of the many interesting topics discussed in a book of over 800 pages. Each page has three columns so there is an immense amount of material covered here. Another interesting group of feature articles pertains to Art as Objects of Patronage and Collecting. These are listed by country, e.g. England, Italy, Spain.
This is a serious art book, and probably would not be of interest to anyone with a very casual interest in the subject. The long article on Perspective, for instance, requires some focusing of the mind. If you've spent some time studying the basics of art, and think that the best way to spend a Sunday afternoon is to tour the local art gallery, then this is the book for you.