Complex sentence: Among the most famous of the freedom suits was that of Dred Scott and his wife Harriet, in a case heard at the Old Courthouse that was based on their having traveled and lived with their master in free states.
Split into simpler sentences: Among the most famous was that of Dred Scott and his wife Harriet, in a case heard at the Old Courthouse. The suit was based on their having traveled and lived with their master in free states.