Wien, I., Museum mit Macia-Thecesien-Denkmal (Austria)
We know the card is from 1946, though looks much older. The front: what you see. The reverse: stamp, a huge special “Befreiungsfeie Wiener Secession” postmark, the attribution “508 M.L.M.W.II”, and no handwriting. (Like a first-day-of-issue cover, though we don’t know.) Grade: 1