Complex sentence: Originally laid out by Lucas Sullivant as the town of Franklinton, the original settlement lay west of the Scioto River, but Sullivant laid out plans to expand east of the river, making plans for what we now know as downtown Columbus.
Split into simpler sentences: Originally laid out by Lucas Sullivant as the town of Franklinton, the original settlement lay west of the Scioto River. However, Sullivant laid out plans to expand east of the river for what we now know as downtown Columbus.