Frauenfeld, capital (since 1803) of Thurgau canton, northern Switzerland, on the Murg River, close to its junction with the Thur River, northeast of Zürich. First mentioned in 1246, it was founded by the count of Kyburg and the abbot of Reichenau on land belonging to the abbot. Frauenfeld (“Field of Our Lady”) passed to the Habsburgs in 1264 and was seized by the Swiss Confederates (Eidgenossen) in 1460, later becoming the seat of the federal Diet from 1712 to 1798. Two great fires (1771 and 1788) destroyed the whole town except the 13th-century castle (now housing the cantonal museum), one house, and the Evangelical church, with 14th-century stained-glass windows. A road and rail junction, Frauenfeld produces machinery, metal products, and food. The population is German speaking with a small Protestant majority. Pop. (2007 est.) 22,253.