Reisterstown is an unincorporated community and census-designated place in Baltimore County, Maryland, United States. As of the 2010 census, it had a population of 25,968.Founded by German immigrant John Reister in 1758, it is located to the northwest of Baltimore. Though it is older than the areas surrounding it, it now serves primarily as a residential suburb of Baltimore. The center is designated the Reisterstown Historic District and listed on the National Register of Historic Places in 1979. Also listed are the Montrose Mansion and Chapel and St. Michael's Church.Just outside the community, to its north, is the small military reservation of Camp Fretterd, which serves as a training site for the Maryland Army National Guard and Air Guard. The Maryland Defense Force is also headquartered at Camp Fretterd.