The former location of the Palais Wittgenstein was on Alleegasse, today’s Argentinierstraße 16, in the 4th district of Vienna, not far from the Karlskirche. Contrary to a possible assumption, the Palais Wittgenstein was not the flag-adorned building on the right side of the image (the current Greek Embassy), but was located on the site of the unassuming building next to it on the left. Unfortunately, the Palais, like the birthplace of Ludwig Wittgenstein in Neuwaldeggerstraße, no longer exists today.

Source: Janik, A.S., & Veigl, H. (1998). Wittgenstein in Wien. Ein biographischer Streifzug durch die Stadt und ihre Geschichte. Springer.

External link: https://magazin.wienmuseum.at/wittgensteins-orte-der-kindheit