Piastowo was formerly part of the German Empire. In the German Empire, the place was called Plassen.
The place is now called Piastowo and belongs to Poland.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Piastowo | German Empire | Znin | before the Versailles Treaty |
| Piastowo | Poland | Żnin | after the Versailles Treaty |
| Plassen | German Empire | Dietfurt (Wartheland) | 1939 |
| Piastowo | Poland | Żnin | 1945 |
| Piastowo | Poland | Bydgoszcz | 1992 |