In 1915, the completion of the Panama Canal was celebrated in San Francisco with a special Panama-Pacific Exposition. To commemorate the event, the San Francisco Mint struck a number of silver and gold coin, including a pair of $50 gold pieces — one round and one octagonal — each depicting a bust of Minerva, Roman goddess of wisdom, art and commerce. The reverse depicts an owl perched on a Ponderosa Pine surrounded by pine cones along with the legend PANAMA-PACIFIC EXPOSITION.