Complex sentence: Since 1978 the US Open tennis tournament has taken place in Flushing Meadows Park at the USTA Billie Jean King National Tennis Center; its center court is Arthur Ashe Stadium and its secondary stadium court is Louis Armstrong Stadium.
Split into simpler sentences: Since 1978 the US Open tennis tournament has taken place in Flushing Meadows Park. Its center court is Arthur Ashe Stadium, and its secondary stadium court is Louis Armstrong Stadium.