Burg Streitwiesen, Medieval castle ruins in Weiten, Austria.

Burg Streitwiesen is a hilltop castle in the Weitental valley near Melk, Lower Austria, consisting of a Bergfried, a Palas, a Langhaus, a chapel and a southwestern tower. The southern outer wall with its round corner towers dates from the Renaissance, when the Rot von Reinprechtspölla family built the site's Renaissance structures.

Streitwiesen is first documented in 1144 as the ancestral seat of an Austrian ministerial family; Ozo von Streitwiesen, from the lords of Stiefern, took his name from the estate. The male line died out in 1396, and the castle passed through owners including the Fleischess (1434–1443) and the Rot von Reinprechtspölla, who built the Renaissance elements and the southern outer wall with round corner towers. From 1797 it belonged to the Habsburg-Lothringen estate of Pöggstall; after 1919 it passed to the war victims' fund and later the federal forests, and in 1972 eleven former scout leaders bought the ruin for a youth castle.

Since 1972 the castle has been run by the Bund zur Errichtung und Erhaltung einer Österreichischen Jugendburg, founded by eleven former group leaders of the Österreichischer Pfadfinderbund. Groups still come to work on the buildings and to make music, and the name Streitwiesen comes from the Streitwieser family, who held the castle from 1144 until the male line died out in 1396.

Burg Streitwiesen lies in the Weitental near Melk, in the Waldviertel. The site is run by the Bund zur Errichtung und Erhaltung einer Österreichischen Jugendburg, whose groups stay there for work camps and hikes through the Waldviertel; visitors should check with the association in Vienna before coming, as the castle serves its member groups rather than regular opening hours.

The castle was bought in summer 1972 by eleven former group leaders of the Austrian Scout Association, who restored the ruin as a youth castle. Its model was the Nerother Burg Waldeck in the Hunsrück. Karl Turetschek was elected chairman and rebuilt the longhouse, chapel, southwest tower and later the palas.