Large Polish commorative medal

This is a huge 70 mm medal
A Polish commemorative bronze medal depicting Bolesław II the Generous (also known as Bolesław II Śmiały). It is part of a series celebrating Polish rulers and historic landmarks.
​Obverse (Front)
​Subject: Bolesław II Śmiały (Bolesław II the Bold/Generous).
​Dates: 1058–1079 (referring to his reign as Duke and later King of Poland).
​Artist/Mint Mark: There is a small inscription at the bottom left: "KOSZALIN", indicating it was likely produced or commissioned in the city of Koszalin, possibly by the Polish Archaeological and Numismatic Society (PTAiN).
​Reverse (Back)
​Subject: Rotunda św. Mikołaja w Cieszynie (St. Nicholas' Rotunda in Cieszyn).
​Significance: This is one of the oldest and best-preserved examples of Romanesque architecture in Poland. It famously appears on the Polish 20 zloty banknote.