The Grand Tour-A Defintion

The Grand Tour was the traditional trip of Europe undertaken by mainly upper-class European young men of means. The custom flourished from about 1660 until the advent of large-scale rail transport in the 1840s, and was associated with a standard itinerary. It served as an educational rite of passage. Though primarily associated with the British nobility and wealthy landed gentry, similar trips were made by wealthy young men of Protestant Northern European nations on Continental Europe, and from the second half of the 18th century, by some South and North Americans, among others. The tradition was extended to include more of the middle class after rail and steamship travel made the journey less of a burden, and Thomas Cook made the "Cook's Tour" a byword.
The New York Times in 2008 described the Grand Tour in this way:

Three hundred years ago, wealthy young Englishmen began taking a post-Oxbridge trek through France and Italy in search of art, culture and the roots of Western civilization. With nearly unlimited funds, aristocratic connections and months (or years) to roam, they commissioned paintings, perfected their language skills and mingled with the upper crust of the Continent.

—Gross, Matt., "Lessons From the Frugal Grand Tour." New York Times 5 September 2008.

The primary value of the Grand Tour, it was believed, lay in the exposure both to the cultural legacy of classical antiquity and the Renaissance, and to the aristocratic and fashionably polite society of the European continent. In addition, it provided the only opportunity to view specific works of art, and possibly the only chance to hear certain music. A Grand Tour could last from several months to several years. It was commonly undertaken in the company of a Cicerone, a knowledgeable guide or tutor. The Grand Tour had more than superficial cultural importance; as E. P. Thompson stated, "ruling-class control in the 18th century was located primarily in a cultural hegemony, and only secondarily in an expression of economic or physical (military) power.
After the arrival of steam-powered transportation, around 1825, the Grand Tour custom continued, but it was of a qualitative difference — cheaper to undertake, safer, easier, open to anyone. During much of the 19th century, most educated young men of privilege undertook the Grand Tour. Germany and Switzerland came to be included in a more broadly defined circuit. Later, it became fashionable for young women as well; a trip to Italy, with a spinster aunt as chaperon, was part of the upper-class woman's education, as in E. M. Forster's novel A Room with a View.
For me, I thought of the Grand Tour more in a "If this is Tuesday, this must be Belgium" kind of way, Americans trying to cram seeing all of Europe in 2-weeks. I would love to take 2-3 years to live in Europe, but funds just won't allow, nor is a "Gap Year" 3 to 5 month sojourn possible-not with careers, mortgages, and other responsibilities. So I will have to do the Grand Tour My Way; 7-14 days at a time, one, maybe 2 trips a year until I see all of my must see items. The list is long, so it will take years. How fun!