Palais Althan, Baroque palace in Landstraße, Austria

Palais Althan was a garden palace built in 1732 by Joseph Emanuel Fischer von Erlach for Count Gundacker von Althan, on Ungargasse 63–67 in Vienna's third district, extending on both sides of today's Barichgasse. Its central section had a partly curved mansard roof and a dome described as a trial run for the dome of the Hofburg's Winter Riding School. The garden covered today's Barichgasse 15–35 and 16–44 and Juchgasse 22–42.

In 1726 Count Karl Anton von Harrach bought the vineyard plot where the palace was later built; he sold it in 1729 to Count Gundacker von Althan, who had Joseph Emanuel Fischer von Erlach erect the palace in 1732. In 1745 Althan sold the complex to his stepson Ferdinand Philipp Prince Lobkowitz, who resold it; after several changes of owner it passed to Michael von Barich, who had it demolished.

The street Barichgasse keeps the name of Michael von Barich, the owner who had the palace demolished and the plot divided into 34 parcels, on which houses were built between 1842 and 1845. The palace itself is not to be confused with the Palais Althan-Pouthon in the Alsergrund district.

The palace stood at today's Ungargasse 63–67, with its garden reaching Barichgasse 15–35 and 16–44 and Juchgasse 22–42. The site is now built over with houses from 1842–1845, so no structure of the palace remains. Barichgasse is named after Michael von Barich, who had the palace demolished.

The palace's central section had a partly curved mansard roof and a dome described as a trial run for the dome of the Hofburg's Winter Riding School. The garden covered today's plots Barichgasse 15–35 and 16–44 and Juchgasse 22–42. The palace is not to be confused with Palais Althan-Pouthon in the Alsergrund district.