Janowo was formerly part of the German Empire. In the German Empire, the place was called Hansburg.
The place is now called Janowo and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Hansburg | German Empire | Neidenburg | before the Versailles Treaty |
| Janowo | Poland | Działdowo | after the Versailles Treaty |
| Hansburg | German Empire | Neidenburg | 1939 |
| Janowo | Poland | Mława | 1945 |
| Janowo | Poland | Ciechanów | 1992 |