Blankenburg (blăng´kənbŏŏrk), Blankenburg am Harz (äm härts), or Bad Blankenburg (bät´), city (1994 pop. 18,680), Saxony-Anhalt, E central Germany. It is a spa located at the northern foot of the Harz Mts. and is also known for its tree and seed nurseries, ironworks, and stone quarries. During his residence in Blankenburg (1837–45), the educator Friedrich Froebel founded the first kindergarten.