Mark Leonard.
Why Europe Will Run the 21st Century.
New York: PublicAffairs / Perseus Books Group, 2005; paperback reprint 2006.
Book information: Publisher; Google Books; Amazon.com; Book webpage at author's website.
This book provides an excellent explanation of the motivations and goals of the European Union project. On the other hand, it was published before the economic weaknesses of the European Monetary Union became apparent after the various financial crises that began in 2008.
Some Mark Leonard links:
Mark Leonard .net, author's website.
Mark Leonard, Wikipedia.