Complex sentence: The 1964 playing of the Liberty Bowl was the first major bowl game ever played indoors, and had been shifted to Atlantic City after the bowl was played for its initial five years outdoors in Philadelphia Stadium, often in temperatures below freezing.
Split into simpler sentences: The 1964 playing of the Liberty Bowl was the first major bowl game ever played indoors. The venue had been shifted to Atlantic City after the bowl was played for its initial five years outdoors in Philadelphia Stadium, often in temperatures below freezing.