Sopron was an important town in the Austro-Hungarian Empire. After the World War I it became part of Austria. But the townspeople were not happy with this and in December 1921 they voted that the city should be part of Hungary. Since that day the city has been called "Civitas Fidelissima", ("The Most Loyal Town" which in Hungarian is "A Leghűségesebb Város"). A holiday is held every year to celebrate.