The reserve „Lasek Miejski nad Olzą” (The City Grove by the Olza River) is one of the two similar protected areas in Cieszyn (the other one is "„The City Grove by the Pucówka River) of a plant called cieszynianka and a part of the oak-hornbeam woodland. The City Grove by the Olza River is a partial flora reserve. It was created in 1961 and covers an area of 3.23 hectares. It is situated on the slopes of the Olza valley, in the southern part of Cieszyn.