Complex sentence: It runs through the heart of Downtown Chicago and ends at the southern city limits, 127th St. at the Little Calumet River.It's intersection with Madison Street marks the base point for Chicago's address system.
Split into simpler sentences: It runs through the heart of Downtown Chicago and ends at the southern city limits, 127th St. at the Little Calumet River. Its intersection with Madison Street marks the base point for Chicago's address system.