Heidelberg Raceway and Sports Arena. Opened in 1948, this former Pittsburgh Racing Assoc. racetrack was the site of the 1956 final performance of Ringling Bros. and Barnum & Bailey Circus under the Big Top. Rising railroad costs, changing technology, labor troubles, space issues, and competition from TV led to this end of an era in entertainment history. The site of early NASCAR races, it boasted several records and brought acclaim to local and national racers before closing in 1973.