Complex sentence: On the northeast side of town are the Berkhamsted and Northchurch commons, the largest in the Chilterns at, and forming a large arc running from Northchurch, through Frithsden, and down to Potten End.
Split into simpler sentences: On the northeast side of town are the Berkhamsted and Northchurch commons, the largest in the Chilterns, at. The commons form a large arc, running from Northchurch, through Frithsden, and down to Potten End.