Kluczewo was formerly part of the German Empire. In the German Empire, the place was called Schlüsselberg.
The place is now called Kluczewo and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Kluczewo | Russian Empire | Serpec | 1914 |
| Kluczewo | Poland | Sierpc | 1919 |
| Schlüsselberg | German Empire | Sichelberg | 1939 |
| Kluczewo Duże | Poland | Żuromin | 1945 |
| Kluczewo | Poland | Ciechanów | 1992 |