Ladies and gentlemen, start your checkbooks!

An unprecedented private collection of some of the world's rarest and most iconic sports cars are getting ready to hit the auction block.

The RM Sotheby's auction, held during the Pebble Beach Concours D'Elegance in Monterey, California, isn't until August but the list of cars available is pretty jaw-dropping. The sale is part of the largest annual gathering of collector cars and enthusiasts worldwide.

Read MoreAmid revved up car market, Amelia's Concours fires up

The "Pinnacle Portfolio" includes a bookend pair of Bugatti Veyrons and the 400th and final Enzo gifted to the late Pope John Paul II.

The crown jewel is a McLaren F1 sports car carrying a pre-sale estimate of $12 million dollars.

The 63rd McLaren F1 ever built, this is arguably one of the greatest racing-based vehicles in automotive history, capable of blistering speeds from the 691-horsepower LM engine.

A similar McLaren F1 sold for a record $8.47 million dollars at the 2013 Pebble Beach Concours D'Elegance.

Also heading for auction is a 1964 Ferrari 250 LM. Rarer even than a 250 GTO it was shown at the 1964 Earls Court Motor Show and raced frequently throughout England with great success.

This one raced the 24 hours of Le Mans Classic twice, and is 100 percent intact with all its original mechanical components.

A Ferrari 250 LM sold at auction last year for $11.5 million dollars.

Read More Most beautiful Ferraris of all time

The auction takes place Sunday, August 13th on the famed eighteenth hole at Pebble Beach Golf Links.