The town twinning between Bad Soden am Taunus and Franzensbad in the Czech Republic has existed for 30 years now. The then Mayor of Bad Soden, Berthold Gall, and Frantisek Zima, former Mayor of Franzensbad, signed the document on January 18, 1992 during the New Year's reception in Bad Soden am Taunus. At the same time there was an exhibition in the foyer of the Kurhaus about the town of Franzensbad, Františkovy Lázně in Czech.
Františkovy Lázně has been a UNESCO World Heritage City since 2021. Franzensbad is around 380 kilometers from Bad Soden am Taunus. The partner cities have also exchanged names, because in Bad Soden am Taunus there is the "Franzensbader Platz" and in Franzensbad the "Bad Soden Promenade".