The area has been inhabited sinceMesolithic times. The flint tools found here from that era (6000–4500 BC) are clearly defined and known as theOldesloer Stufe. For a number of years in the 18th century theMoravian Church had a congregation in Bad Oldesloe. It was called "Pilgerruh", i.e. "Pilgrims' Rest". It was given up because of difficulties with the Danish Church authorities. At that time, theDuchy of Holstein was ruled by the kings ofDenmark within theHoly Roman Empire.
On 24 April 1945, the town was heavily bombed byAllied forces in the final days of theSecond World War in Germany. Threehundred buildings were destroyed, and 706 people were killed as a result of the operation.[2]
16th century Mennokate: Memorial forMenno Simons, founder andeponym of theMennonites, a group ofanabaptists. He had some of his works printed in this building.
^Kuhlmann-Schultz, Kerstin (10 September 2014)."24. April 1945 — Oldesloes schwarzer Tag" [24 April 1945 - Oldesloe's black day].Lübecker Nachrichten (in German). Retrieved3 May 2019.