Complex sentence: Roy Benjamin, whose architectural firm eventually became KBJ Architects, designed the theater building in the Italian Renaissance style, along with more than 200 theaters throughout Florida and the southeast United States including Downtown Jacksonville's Florida Theatre.
Split into simpler sentences: Roy Benjamin, whose architectural firm eventually became KBJ Architects, designed the theater building in the Italian Renaissance style. Benjamin went on to design more than 200 theaters throughout Florida and the southeastern United States, including Downtown Jacksonville's Florida Theatre.