The round Panama-Pacific Exposition $50s did not sell as well as their octagonal counterparts at the time of issue and many were melted. From the mintage of 1,500 pieces only 483 examples were sold, with the remaining 1,017 coins melted, making this the rarest collectable classic commemorative type. Elusive at all levels of preservation, the round examples are especially challenging to locate in problem free Choice and higher Mint State grades.

The obverse depicts the goddess Athena wearing with her stylized crested war helmet pushed back on her head, exposing her face in a gesture of peace. Arcing across her shoulder is the date in Roman numbers, MCMXV for 1915, and this is only the second time Roman numerals were used on a United States coin for the date, the other being the famed 1907 High Relief $20s by Saint-Gaudens. The motto In God We Trust appears in the field above her helmet, and UNITED STATE OF AMERICA / FIFTY DOLLARS surrounds in a thick border at the periphery. Athena is the goddess of wisdom, skill, agriculture, horticulture, spinning and weaving and is known to have taught her followers how to use olives, both for cooking, eating and for lighting their oil in lamps at night. On the reverse an owl is depicted, perhaps as a watchful and powerful predator as the European counties continued their war, and is perched on a branch of a pine tree, thought to be a Ponderosa pine in light of the immense pine cones also depicted on the coin. The motto E PLURIBUS UNUM sits behind the wise bird, and the obverse theme of large legends surrounding is repeated with PANAMA-PACIFIC EXPOSITION / SAN FRANCISCO. Complaints that the people of America would not understand the symbolism of Athena and her owl were overruled and Robert Aiken's designs were employed to strike these majestic $50 coins. Thoughts of depicting some part of the Panama Canal itself were discarded, even the locks used to raise the ships over the land would have been difficult to translate into a scene on a coin. Athena was more in keeping with the educational aspects of the Exposition and the owl of watchful wisdom spanned the themes mentioned with grace. Most of the Round $50 pieces were sold individually for $100 at the Exposition, a few were sold in sets with the other coins of the Exposition and a dozen were reportedly sold in double sets which showed both the obverse and reverse designs of each coin.

The example to the left was sold by Stack's Bowers Galleries in the D. Brent Pogue Part VII Auction, where it realized $192,000.