The SS1 Aurelia highway runs along Italy’s Tuscan coast, which makes it one of the most familiar holiday routes in the nation. Among the sites along the road is an oddity that never fails to catch the eye of drivers and passengers: a sign, at kilometer 273, on the edge of the city limits of Cecina. On it, an arrow points toward a small exit on the big highway: “La California.” “That sign is always brand new,” says local historian Marco Andrenacci. “It gets stolen at least once a year,…