London
It starts as a hairline fracture at the building's western entrance, following the contours of the vast hall down into an ever-widening fissure. It reminds some visitors of an earthquake, not that too many at the Tate Modern have actually lived through one.
Perhaps that's why three people, possibly mesmerised by the artwork, have fallen into Colombian artist Doris Salcedo's 167-metre-long exhibit, which splits the polished concrete floor of the Turbine Hall in two.
How odd to go to an exhibition to see a 167-metre twisting plaster fissure and then fall down it, as if you are genuinely surprised it is there.
Still, somewhat aptly, the piece is called Shibboleth, the Hebrew word for separating the inferior from superior - that is, separating the thousands who haven't fallen down it from the lame trio who have.
Apparently the plasterwork fissure represents the divisions between creed, colour, class and culture, or so instructs Time Out magazine. Whatever the case, to most people it is simply a very large crack. It is not the first piece of 'destination art' to have caused ructions at the Tate. Three years ago there was the sodium sunset, or Olafur Eliasson's Weather Project, an ominous false sun that brought Londoners inside to 'sunbathe' day and night.
Last year there was Rachel Whiteread's Embankment, white cardboard boxes piled high, redolent of an oversized sugar lump factory. More recently we had Carsten Holler's Test Site, a giant helter-skelter, or spiral slide, that attracted queues of children and childish parents.
