Riley’s retirement from his factory job gave him the opportunity to devote full time to his art.
In 1975 Riley conceived the idea of creating a 14x40 foot mural in the Bridgeport Connecticut Library that would depict the history of that city. He began work in October 1976, and spent the next eight years of his life researching the city’s history, while creating his monumental work.
The act of drawing on a wall surface with a brush using reddish sepia is a rather outdated art technique anchored in Renaissance tradition. It becomes symbolic of the story Riley tells about the rapid disappearance of manual craftsmanship:
The New York Times called him "A 'Historian' for Bridgeport." In his interview with the Times, Riley said:
The mural was completed in 1984 shortly before his death and stands today as a memorial to his lifelong interest in art and in the City of Bridgeport.