Troiburg was formerly part of the German Empire. In the German Empire, the place was called Troiburg.
The place is now called Trøjborg and belongs to Denmark.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Troiburg | German Empire | Tondern | before the Versailles Treaty |
| Trøjborg | Denmark | Tønder | after the Versailles Treaty |
| Trøjborg | Denmark | Sønderjylland | 1993 |