There are perhaps no two more famous United States commemorative coins than the 1915-S Panama-Pacific Round $50 and its same-year octagonal counterpart. Struck to commemorate the 1915 Panama-Pacific Exposition held in San Francisco, the Pan-Pac Round $50 was designed by Robert Aitken, with the obverse bearing a helmeted head of Minerva, while the reverse carries an owl that symbolizes wisdom. It was then the highest-denomination coin the United States Mint had struck and, alongside the octagonal $50, was made with three other gold and silver Pan-Pac commemorative coins.

The Pan-Pac Round $50 is very rare, with only 483 distributed. About 75% still exist, and most of them are known in uncirculated condition. On the occasion that they come to the marketplace, usually by way of public sale, they are encountered in grades of MS60-65. A very rare few are known in the MS66 grade range. Pieces grading about MS64 and up are reliably six-figure coins, while all others command robust five-figure prices.