Baltimore County is a county located in the northern part of the U.S. state of Maryland. As of the 2010 census, the population was 805,029, making it the third-most populous county in Maryland. Its county seat is in Towson, in the north-central section just north of the adjacent City of Baltimore. The name of the County was derived from the barony of the Proprietor of the Calverts' new colony in the Province of Maryland, Cecil Calvert, 2nd Baron Baltimore, (1605-1675),, and the town of "Baltimore" in County Cork, of southern coastal Ireland.