Castlewood is a census-designated place (CDP) in western Russell County, Virginia, United States.

Castle purchased the land from the Shawnee Indians, for very little in trade, reportedly just a "hound dog, a knife, and a shot of whiskey".

Castle's father, Peter Cassell, was a German emigrant to Pennsylvania who was influential in the Dutch movement to America.

The name was modified to Castlewood by the United States Postal Service in the late 1800s, as a simplification of the original spelling and pronunciation, which was common during this time period.

According to the United States Census Bureau, the CDP has a total area of 7.2 square miles (18.7 km2), of which 99.86% is land and 0.14% is water.

Bandmates Isaac Gibson (lead singer/guitarist), Chase Chafin (bassist), Bus Shelton (guitarist), and Noah Patrick (pedal steel) formed the group in Castlewood at a house located at 49 Winchester Street around 2015.