The Toaping Castle was a house in present-day Greenbelt, Maryland, built circa 1750 by Charles, Isaac and Nathan Walker, three brothers who fled to America from Scotland. The Walker brothers constructed the house on a 188-acre (0.76 km2) land grant in an area that eventually became Greenbelt. Samuel Hamilton Walker was born at Toaping Castle in 1817 and later served as a Texas Ranger and U.S.