Interior of the Palm House, Carl Blechen
On Google Art Project. Downloadable high-resolution version on Wikimedia Commons. Original is in the Alte Nationalgalerie, Staatliche Museen zu Berlin.
I had seen reproductions of this painting before, and has assumed it was a watercolor from the translucency of the leaves and the graphic nature of some of the architectural elements, but it’s oil on paper, laid on canvas.