Complex sentence: These buildings had been the main production and warehouse facilities of the Bunte Candy Company since 1959 before being sold to the American Candy Company in 1990, which then sold the plant to Farley.
Split into simpler sentences: These buildings had been the main production and warehouse facilities of the Bunte Candy Company. They were sold to the American Candy Company in 1990, which then turned around and sold the them to Farley.