Great Books of the Western World
Great Books of the Western World is a series of books originally published in the United States in 1952 by Encyclopædia Britannica Inc. in an attempt to present the western canon in a single package of 54 volumes. The original editors had three criteria for including a book in the series: the book must be relevant to contemporary matters, and not only important in its historical context; it must be rewarding to re-read; and it must be a part of "the great conversation about the great ideas", relevant to at least 25 of the 102 great ideas identified by the editors.
The series is now in its second edition and contains 60 volumes. (Wikipedia - http://en.wikipedia.org/wiki/Great_Books_of_the_Western_World)
In order to aid people reading through all these books, Britannica created a Ten Year Reading Plan, each containing between 20 and 25 of the Great Books of the Western World. As many of those books are in the public domain, a number of them can be found as audio on LibriVox. Here are links to the individual years of the 10 years reading plan; each book has a link to its Librivox version, if there is one, or a link to a public domain text.
All books on the Ten Year Reading Plan can be found on a glance here.