New Castle Court House Museum, also known as New Castle Courthouse 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 a small part of the border between Delaware and Maryland. It is one of the oldest courthouses in the United States.
It was declared a National Historic Landmark in 1972.
The building known today as the "Old Court House" was built in sections during three centuries of colonial and federal government. Prior to the Revolution it served as the meeting house for the governments of the three counties comprising Delaware. For one year (1776–1777) it served as the state house of Delaware. Thence it became the New Castle County courthouse for three centuries. An occasional court held there serves to keep alive the claim that this building is the oldest continuously used chamber of justice in the United States.
The building became part of First State National Monument in 2013.
The Old Court House is open for tours 10 am - 3:30 pm (Monday - Saturday) 1:30 pm - 4:30 pm (Sunday). Admission is free, donations are accepted.