Light after death in Texas

The last work by the late Dan Flavin is unveiled in a series of ex-army huts this week. Charles Darwent pays homage to one of Minimalism's most important installations

Next Saturday, all being well, Tate Gallery director Sir Nicholas Serota will do an unlikely thing. He will sit down at a trestle table in the middle of a dusty road and, to the strains of a Mexican mariachi band, he will tuck into a plateful of burritos, tamales and refried beans. (Whether he will actually wear a checked shirt and stetson for the occasion has yet to be confirmed.) If this seems a frivolous way for the notoriously high-minded gallerist to be carrying on, rest assured that it is in a good cause. The tacofest will celebrate both the birthday of an institution dear to Sir Nicholas' heart and the final completion, after 14 long years of wrangling, of one of the most important pieces of Minimalist art ever made.

Next Saturday, all being well, Tate Gallery director Sir Nicholas Serota will do an unlikely thing. He will sit down at a trestle table in the middle of a dusty road and, to the strains of a Mexican mariachi band, he will tuck into a plateful of burritos, tamales and refried beans. (Whether he will actually wear a checked shirt and stetson for the occasion has yet to be confirmed.) If this seems a frivolous way for the notoriously high-minded gallerist to be carrying on, rest assured that it is in a good cause. The tacofest will celebrate both the birthday of an institution dear to Sir Nicholas' heart and the final completion, after 14 long years of wrangling, of one of the most important pieces of Minimalist art ever made.

The institution in question is the Chinati Foundation, founded in 1986 by the late American Minimalist sculptor, Donald Judd, in the redundant army base of a half-horse Texan town called Marfa. (Serota is on the Foundation's board of directors.) One of the Sixties generation of American museum-haters, Judd intended the foundation to function as an anti-gallery. Instead of the typical anthology hang that crams different artists into a single room, Marfa's artillery sheds and lavatory blocks would offer large-scale showing spaces for permanent displays of Judd's own work and that of a select band of chosen Juddites.

Among these was to be Judd's fellow-Minimalist, Dan Flavin, who submitted plans for a neon installation to occupy a row of six decaying Marfa mess huts. Financial problems - the Chinati Foundation had $400 in the bank when Judd died in 1994 - had kept Flavin's constantly evolving project on hold during Judd's life. A blazing row between Flavin and Judd (a thing to which Marfa's creator was prone) meant that it was still there when Flavin himself died in 1996. Which will make next Saturday's annual Chinati hoe-down in Marfa's main street a doubly happy affair. Trojan efforts by Chinati's small staff have not merely kept the foundation alive, but have finally allowed Flavin's $1.7 million Untitled (Marfa project) to see the light of day.

Or, rather, not: for if there is one thing that Untitled (Marfa project) isn't about, it is daylight. The work goes like this. Flavin (via his surviving assistant, Steve Morse) has sealed off the centre-stroke of each U-shaped hut with a pair of diagonal white walls. In each of these are two rhomboidal doorways, joined to their corresponding doorways in the other wing of the hut by a pair of leftward-leaning corridors. Passage through each corridor is blocked by a gate of 16 diagonal neon strips, a Flavin hallmark: in alternate huts, these gates either bar the doorways themselves or form barriers halfway down the corridors. In the first two huts, the strip lights, placed back-to-back in pairs of eight, are pink and green; in the next two they are blue and yellow; and in the final pair, a combination of all four colours.

So far, so Flavin. As with most Minimalist work, the trick here is in the tinyness of the intervention. Flavin's chosen materials are MDF, white paint and commercial neon strips; his vocabulary is the 76-degree angle of the doorways, the lines of the cut-stone floors, the difference between colour seen directly and colour deflected off of walls. Untitled (Marfa project) is, if you like, the story of active and contemplative light. In those huts where the neon gates are in the doorways, the effect is Op-ish: your eyes are mesmerised into reading the colours as quivering 2-D Bridget Riley stripes. In those where the strips are placed centrally, the deferred light - pink and green resolved into gold, blue and yellow into silver - becomes an architectural element, melting the rhomboidal geometry of the doorways like butter. There are all kinds of antitheses at work in Untitled (Marfa project): corridors that both lure and bar, light that defines space and defies it. Mostly, though, there is a wry game going on between the world outside Flavin's huts and the world within them. Turn away from the artist's patently manufactured vision to the windows of the huts and you suddenly find the reality beyond them looking less than real; Edward Hopper by way of René Magritte.

What makes Untitled (Marfa project) Flavin's undoubted swan-song is the Judd-ish scale of Marfa. This is not a matter of size but of process. To get from one hut to another, you are forced to emerge into the radiant heat of a Texas afternoon and follow a path through the kind of scrub that puts you in mind of rattlesnakes. (This is not entirely urban paranoia. Steffen Boddeker, Chinati's press man, had found one shortly before my visit.) Although Flavin was against such things, the experience is curiously religious: a series of journeys into the wilderness punctuated by moments of claustral abstraction. The process also raises all kinds of questions about the role memory plays in the way we see things. Do you have to do all six huts to have seen Untitled (Marfa project)? Are we meant to read them separately or sequentially? How long do we stop in each, and where do we stand? You may not feel like St Paul by the end of all this, but you will have seen a light in the desert; and whatever your old views on Flavin, you will have been converted by it.

* Dan Flavin's 'Untitled (Marfa project)': from 7 October. Tours of the Chinati Foundation, Marfa, Texas (00 1 915 729 4362) are on Thursdays, Fridays and Saturdays at 1pm and 3pm, or by appointment