Complex sentence: In 1885, the Western Pennsylvania Exposition Society, commonly called the Pittsburgh Exposition, were determined to have a venue that offered the feel of a county fair with the mystique of a World's Fair.
Split into simpler sentences: In 1885, Western Pennsylvania Exposition Society, commonly called the Pittsburgh Exposition Society, was organized. The Pittsburgh Exposition, were determined to have a venue that offered the feel of a county fair with the mystique of a World's Fair.