Kunstsammlung Nordrhein-Westfalen — Düsseldorf, North Rhine-Westphalia, Germany

This one's built from strips of coloured tape rather than paint, and it was never finished. A curator worked out a few years back that it's likely been hanging upside down since the 1940s — and from what I've read they're leaving it that way, because the tape has gone so fragile that turning it now could take the whole thing apart.

This was the last of his ten numbered 'Compositions' — the works he considered his most important, apart from the smaller 'Improvisations' he made along the way. He mostly avoided black in his own paintings, since he linked it with endings, so it's a little strange that's the color he chose to close the series on.

There's supposedly cavalry hidden in this one — apparently based on Cossacks riding into Moscow during the 1905 uprising, from a period when he still let recognizable figures sneak into otherwise abstract paintings.