Kaltbründlberg, Mountain summit in Hietzing district, Vienna, Austria.

Kaltbründlberg is a wooded hill in the Lainzer Tiergarten, in Vienna's Hietzing district, reaching 508 metres. Its roughly 500-metre-wide summit plateau carries the Hubertuswarte, a lookout tower on the highest knoll. The hill belongs to the Wienerwald range, and parts of the Gütenbach spring area lie on its southern slopes.

The name Kaltbründlberg was first recorded in 1925, in the forms Kaltbrünnlberg and Kalter Brünnlberg. It derives from the Kaltbründlwiese meadow to the south, documented since 1788 as Brünndlwiese, which in turn was named after a cold spring of the Gütenbach at its eastern edge.

The mountain sits within the Lainzer Tiergarten game reserve and draws visitors who follow the marked paths and use the observation points. The trails show how locals and tourists treat this spot as an escape from city life.

The location in Vienna's 13th district provides straightforward access to several hiking paths with multiple starting points throughout the area. You can visit any time of year and choose routes based on your fitness level and interests.

The southern slopes contain sections of the Gütenbach's source, which flows through flysch rock formations into the Reiche Liesing stream. This geological feature reveals how mountain water moves through the landscape and connects different ecosystems.