The Penn–Calvert boundary dispute was a long-running legal conflict between William Penn and his heirs on one side, and Charles Calvert, 3rd Baron Baltimore and his heirs on the other side. The overlapping nature of their charters of land in Colonial America required numerous attempts at mediation, surveying, and intervention by the king and courts of England to ultimately be resolved. Subsequent questions over these charters have also been adjudicated by American arbitrators and the Supreme Court of the United States. The boundary dispute shaped the eventual borders of five U.S. states: Pennsylvania, Maryland, Delaware, New Jersey, and West Virginia.
Charles Calvert, 3rd Baron Baltimore, Proprietor of Maryland
The cupola of the New Castle Court House was used as the center of the Twelve Mile Circle; the boundary Commissions met here numerous times over the years.
The New Castle Court House Museum is the center of a circle with a 12-mile radius that defines most of the border between the states of Delaware and Pennsylvania and parts of the borders between Delaware and New Jersey and Maryland.
The Court House's Assembly Room
Justice Samuel Chase, who was impeached over his actions in the Court House
The Courtroom