Held two weeks in advance of the famed Formula 1 Grand Prix of Monaco, RM Auctions’ May 10 sale in Monaco brings a diverse selection of classic automobiles to the block, along with several non-vehicle lots with historic significance to the principality. Highlights of the automotive offerings include a 1966 Ferrari 275 GTB/C, the 1956 Maserati 450S Prototype, and a 1959 Ferrari 250 GT Cabriolet Series I—each of which carries a presale high estimate of $6.9 million. Other top lots include the beautifully curvace…