Kreuzlingen is a municipality in the district of Kreuzlingen in the canton of Thurgau in north-eastern Switzerland. It is the seat of the district and is the second-largest city of the canton, after Frauenfeld, with a population of about 22,000. Together with the adjoining city of Konstanz just across the border in Germany, Kreuzlingen is part of the largest conurbation on Lake Constance with a population of almost 120,000.

Thurgau, anglicized as Thurgovia, and formally as the Canton of Thurgau, is one of the 26 cantons forming the Swiss Confederation. It is composed of five districts. Its capital is Frauenfeld.