Joseph Beuys, z.B. Skulptur, 1978, print on paper, 833 x 592 mm, Tate/National Galleries of Scotland.
Not so much a work of art, more a piece of paper telling you where some are. It's an exhibition poster. It is a good one. It tells you where and when the exhibition is, and what's in it. You can't really ask for much more. (Actually, entry price would be nice. And directions from Dudley, on foot.)
What's of interest here is why the Tate has got it in the first place. It has quite a few Beuys exhibition posters. Of all the many gaps in their collection, the one marked 'Joseph Beuys exhibition posters' was one they chose to fill back in 2008. This was because they were making a collection of Beuys-related material to be sent round the country as part of their Artist Rooms project. It is currently in Worcester.
At the moment, the acquisition makes sense. But one day, in the far future, the Artist Room project will be no more, and some future mutant-person rummaging in the vaults will ask, why on earth do we have so many Beuys exhibition posters? Another mutant-person will shrug, and wonder why the money wasn't spent on a work by the Greatest of All Artists, Ron Wood. Then they'll put on their jet-packs, fly off into the Sun where they live, and forget all about it.