Twin Cities
- Lublin (Republic of Poland)
- Olsztyn (Republic of Poland)
- Rzeszów (Republic of Poland)
- Toruń (Republic of Poland)
- Zamość (Republic of Poland)
- Chełm (Republic of Poland)
- Białystok (Republic of Poland)
- Xiangtan (People's Republic of China)
- Gori (Georgia)
- Trakai District (Republic of Lithuania)
- Kaunas (Republic of Lithuania)
- Taurage District (Republic of Lithuania)
- Alba Iulia (Romania)
- Bandirma (Republic of Turkey)
- Lippe District (Federal Republic of Germany)
- Kyjov (Czech Republic)
- Patras (Greece)
- Svit (Slovak Republic)
- Schweinfurt (Federal Republic of Germany)
- Würzburg (Federal Republic of Germany)