Opolskie defensive walls have survived to this day only in a small fragment located in the monastery of the nuns of Notre Dame. Some of the original walls were reconstructed during conservation work. Today fragments of preserved and reconstructed walls can be seen at ul. Kolegiacka, ul. Łangowskiego, ul. Omanczyk, ul. Blade and also along the Młynówka canal in the vicinity of the Old Town.
The original defensive walls were built at the turn of the 12th and 13th centuries on the initiative of Opole Prince Duke Bolka. According to the then tradition, they surrounded the town by allowing one of the gates to pass through: Bytom, Zamkowa, Biskupia, Odrzańska and Goslawica. There was also a tower of St. Barbara, serving as a prison for clerics. From the former defensive team, the original Wilcza Tower on the monastery grounds has survived, and the Cathedral is partially reconstructed by the Barbary Tower. Formerly, at the outlet of the current Osmańczyk Street there was also the Storks Nest.