Complex sentence: Arguably, this song is considered to be one of the most popular and best known alma maters in the United States and the world as the tune has been adopted since by dozens of universities, colleges, and high schools worldwide.
Split into simpler sentences: Arguably, this song is considered to be one of the most popular and best known alma maters in the United States. The tune has been adopted since by dozens of universities, colleges, and high schools worldwide.