Linz is the capital of Upper Austria and third-largest city in Austria. Located on the river Danube, the city is in the far north of Austria, 30 km sout…Linz is the capital of Upper Austria and third-largest city in Austria. Located on the river Danube, the city is in the far north of Austria, 30 km south of the border with the Czech Republic. As of 1 January 2024, the city has a population of 212,538. It is the 7th largest of all cities on the Danube river.