 Affluent Americans with the flexibility to work remotely have been snapping up luxury houses on the French Riviera, sparking a surge in property prices in a region known for its stunning beaches, fancy yachts and the glamorous Cannes Film Festival. Prices of homes valued above $16 million along France's southeastern coast rose between 15 and 20 percent in the five years through 2023, outperforming the 13 percent gains in London over the same period.