John I, Margrave of Brandenburg was from 1220 until his death Margrave of Brandenburg, jointly with his brother Otto III "the Pious".
Plauer See, the scene of a battle against Magdeburg in 1229
John I (sitting) and Otto III studying the (alleged) city charter of Berlin and Cölln (now in the Spandau Citadel)
Berlin and Cölln around 1230
Albert II was a member of the House of Ascania who ruled as the margrave of Brandenburg from 1205 until his death in 1220.
