Hörndlwald, Forest and natural monument in Hietzing, Vienna, Austria

Hörndlwald is a forest and recreation area in Vienna's 13th district, Hietzing, between the Geriatriezentrum Am Wienerwald to the east, the Friedensstadt settlement to the south and the Lainzer Tiergarten to the west. Its highest point reaches 306 m above sea level. The northern half remains wooded, while the southern half was cleared in the early 1920s for the Friedensstadt settlement.

Hörndlwald was once part of the walled Lainzer Tiergarten, reaching from Joseph-Lister-Gasse to the Hermesstraße leading to the Hermesvilla. In the early 1920s its southern half was cleared for the Friedensstadt settlement, while the northern half stayed wooded. After 1945 the area served refugee care; from 1950/51 the Volkshilfe Wien held it as tenant until 2011.

The forest's name comes from the Volkshilfe Wien holiday home built here in 1950/51 on Josef Afritsch's initiative, with support from Swedish social democrats; it was named the Josef-Afritsch-Heim in 1965. In July 1952 the Socialist Youth International held an IUSY camp there with 32,000 participants from 36 countries, and a international falcon camp followed in 1958.

Access is through several marked walking trails that wind through the forest and suit different fitness levels. The open areas work well for spending time, having a picnic, or simply watching the natural surroundings.

The southern half of the Hörndlwald was cleared in the early 1920s to make way for the Friedensstadt settlement, leaving only the northern half wooded. The site of the demolished Josef-Afritsch-Heim, a 1950/51 guesthouse by architects Boeck, Hoch and Bergmann, was renatured after 2019.