The Louisiana Purchase Exposition (informally known as the St. Louis World's Fair) was the event of the century.

Over the course of about eight months, nearly 19.7 million people visited Forest park to see exhibitions from more than 60 countries and the many, many structures that were built for the event.

Dig into these pictures provided by the Missouri Historical Society to check out some of the completely mind-blowing scenes that attendees got to see in St. Louis way back in 1904.

Photos by the Missouri Historical Society