Complex sentence: At one point, Clark went to his companies trading floor which stood at the east side of his tower, where he saw fellow employees of his peering out the windows, watching people jump to their deaths in the adjacent tower.
Split into simpler sentences: At one point, Clark went to his company's trading floor which stood at the east side of his tower. When he arrived, he saw his co-workers peering out the windows, watching people jump to their deaths from the adjacent tower.