17th-18th century - Leisure travel begins when Northern European aristocrats send their sons to Italy and Greece on a "Grand Tour" to learn about the culture.
19th century - railroads and steamships made travel much faster, and the rise of an urban upper-middle class with disposable income made travel accessible to large numbers of people for the first time. The French Riviera and mountain resorts in the Alps become developed around this time.
1930's - commercial air travel begins, but is a luxury only for the very rich.
1950's -