Grottau was formerly part of the German Empire. In the German Empire, the place was called Grottau.
The place is now called Hrádek nad Nisou and belongs to Czech Republic.
| Historical place name | Country | Administration | Time |
|---|---|---|---|
| Grottau | Austro-Hungary | Reichenberg | before the Treaty of Saint-Germain |
| Hrádek | Austro-Hungary | Reichenberg | before the Treaty of Saint-Germain |
| Hrádek nad Nisou | Czechoslovakia | Liberec (venkov) | after the Treaty of Saint-Germain |
| Grottau | Czechoslovakia | Liberec (venkov) | after the Treaty of Saint-Germain |
| Grottau | German Empire | Reichenberg | 1938 |
| Hrádek nad Nisou | Czechoslovakia | Liberec | 1945 |
| Hrádek nad Nisou | Czechoslovakia | Liberec | 1992 |
| Hrádek nad Nisou | Czech Republic | Liberec | 1993 |