1915-S Panama-Pacific Exposition $50. Round. MS-65 (PCGS). Secure Holder.A remarkably well preserved and smooth-looking example of this legendary rarity among classic U.S. Mint commemorative coinage. Satiny medium gold surfaces are boldly defined throughout with strong eye appeal to match superior technical quality. The obverse of this impressive type depicts Liberty as Athena with her helmet pitched up upon her head in the expected fashion of the Greeks, surrounded by the legend UNITED STATES OF AMERICA above and the denomination FIFTY DOLLARS below. The motto IN GOD WE TRUST is located in the upper left field. For the reverse the designer, Robert Aitken, features a large owl facing nearly forward, perched on a thick pine branch, with large pine cones below and in the background. The motto E PLURIBUS UNUM is tucked into the field behind the owl. Matching the obverse is a round band at the perimeter which notes the name and place of the Exposition. The octagonal pieces, but not their round counterparts, include an extra border with dolphins that symbolize the continuous waterway created by the opening of the Panama Canal. The round version of the Panama-Pacific Exposition $50s did not sell as well as the octagonal style at the time of issue in 1915, hence a greater percentage of the mintage was returned to the Mint for melting. In fact, of the 1,500 round examples struck, only 483 were distributed to contemporary collectors, which paltry total confirms this type as the rarest collectible U.S. Mint commemorative coin. Gems such as this are in the distinct minority among survivors, many of which are impaired due to mishandling, and few of which grade finer than MS-64. A simply incredible example of this prized issue, featured in the popular reference <em>100 Greatest U.S. Coins</em> by Jeff Garrett and Ron Guth.