Went to see the Psycho Buildings exhibition at the Hayward Gallery yesterday, which I recommend if you like big-impact sculptural pieces, although be warned that the signature work, Normally, Proceeding and Unrestricted With Without Title, a temporary boating lake on the roof of one of the Hayward terraces, is currently closed for repairs. There's plenty else to expand the mind: Fallen Star by Do Ho Su (a meticulously constructed collision between a huge American-style doll's house and a Korean dwelling), Show Room by Los Carpinteros from Cuba (literally a room exploding, again painstakingly built by suspending all the individual components, breeze block to blue plastic egg tray, from the ceiling on wire to create the effect of an Ikea- furnished room in mid-deconstruction) and Rachel Whiteread's Space (a spooky twilit village made of second-hand doll's houses). Anyway, there's a cinema set up there showing a loop of short films about architecture and art, and the one we caught told the tale of a piece of art I hadn't known about: Robert Smithson's Partially Buried Woodshed at Kent State University. (The film, by Jane Crawford, was called Sheds.) It's a great story.

In brief, Smithson (who died young in a plane crash) was a visiting lecturer at the University in 1970 and was encouraged to produce one of his "earthworks" while there, so he dumped 20 truckloads of earth on top of an existing woodshed in the college grounds until the central lintel collapsed - his way of showing geology consuming human history. The resulting piece of architectural and conceptual "land art" was then supposed to be allowed to be overtaken by the landscape around it, "subject to weathering", in his words, and to become part of history. And boy, did it!

Just over two months after the shed's conception, Kent State was immortalised for all the wrong reasons when National Guardsmen broke up an anti-Vietnam protest by opening fire on unarmed students, killing four of them and shocking the nation, and the world. Someone painted the date on the front of the partially buried shed (MAY 4 KENT 1970) and, unwittingly, it became an emblem for the tragedy that took place there that day, shots that were heard all around the world. Perpetually at the centre of rows about whether it should be preserved, or bulldozed, it was set on fire in 1975, and all dangerous bits taken away. What was left of it stayed there until 1984, when it was cleared for health and safety reasons. The site, though, survived being developed into a car park, and although mature trees surround it (a row of cedars were planted by town planners to make it look prettier for cars hurtling past on the freeway), you can still see the foundations, and people make pilgrimages there.

I can't really publish a photo of it, as they all seem to be owned by the Smithson estate and I don't want to get into trouble. But go and have a look at them using the above link.