Is it farther or further?
Mediterranean seacoast around Genoa, 1630s, from Italian riviera, literally "bank, shore" (see river). In extended use, the coast from Marseilles to La Spezia, which became popular 19c. as a winter resort. Thence adopted (sometimes ironically) in reference to areas of other countries, e.g. American Riviera (Florida, 1887); English Riviera (Devonshire coast, 1882).
Note: Its scenic beauty and mild climate make it a popular vacation area.
Note: The French Riviera is also called the Côte d'Azur (the azure coast).