Williams Ordinary is one of the oldest structures in the county dating back to when Dumfries was still a bustling port town on the Potomac River. Today, the building on Route 1 south (Main Street in Dumfries) is owned by the county government and used as offices for its Historic Preservation Division.
Williams Ordinary was thought to have been built as a tavern in 1760. But new tests revealed the building is newer, dating back to just before George Washington took the Office of the Presidency, to 1786 – 87.