[4] In the 1990s scanty wooden relics of a castle and ceramics were unearthed behind the municipal library in the Market Place (Großer Markt).

The oldest document in which Osterburg was mentioned was written in 1208, and it was described as "oppidum et castrum", i.e. a town with a castle.

[8] Most of the medieval city wall was demolished in the 19th century, but a small was part was left and can be visited beside the school Markgraf-Albrecht-Gymnasium.

[12] The municipal library is in Kreyenbergsches Haus, a half-timbered house dating from 1770 at the Market Place (Großer Markt).

[13] St. Martin's Chapel in the eastern part of Osterburg outside the historical centre was founded in the 12th century and transformed into a small neogothic church in 1868.