Feel like brushing up on your French with some famous neighbors? A fully furnished Turtle Bay mansion at 238 E. 49th St. is on the market as a rental for $23,500 a month.

The four-bedroom, 5½-bathroom mansion, built in 1866, shares gardens with the mansion that banker Olivier Sarkozy, half-brother to the former French president, purchased as a love nest — a gut renovation is reportedly in the works — to share with his much younger fiancée, Mary-Kate Olsen.

How does a private townhouse share a garden?

Turtle Bay Gardens is a shared communal backyard for townhouses bounded by 48th and 49th streets on Second and Third avenues. The listing broker is Debra Stotts, of Town Residential.