Not the last `Supper' after all ...

One street. Two buildings face off across its narrow width. Inside the buildings are two artistic works of the same name, but they are centuries apart in age and worlds apart in style. The little street, Corso Magenta, is one of the most interesting of Milan's old roads. It follows a winding path betwen ancient structures dating from the Renaissance. As it reaches the building designated today as No. 59 - the Palazzo delle Stelline - the Corso is barely 35 feet wide. Just across the narrow way is the Church of Santa Maria delle Grazie.

Inside the church - in the remnants of its Dominican refectory - is Leonardo da Vinci's famous fresco ``The Last Supper,'' which he painted on the wall in tempera between 1495 and 1497. In the refectory of the palazzo is Andy Warhol's latest creation, ``The Last Supper,'' completed just last year. How these two ``Suppers'' came to be across the street from each other is an interesting story. A tale of two `Suppers'

The story begins with the palace itself. Palazzo delle Stelline has been owned for some time by a Milanese bank, the Banca Valtellinese, which a few years ago decided to restore the entire building. Typical of the Renaissance palaces found in Milan, it is a very large square building that extends all the way to the edge of the street. The rooms of the palace are built around a central courtyard, which is planted with flowers, grass, and shrubs. At the backside of the courtyard is a refectory on the ground floor. When the bank restored the palace, it turned this old refectory into an art gallery and put it at the disposal of the Office of Culture of the City of Milan for appropriate exhibits.

Now enters into the story Alexandre Iolas, an octogenarian Greek connoisseur of art and the owner of galleries in New York, London, and Paris. He first discovered Andy Warhol in the late 1950s and sponsored the first New York exhibit of Mr. Warhol's work when the artist was still employed by Glamour, manufacturers of high-style women's shoes. (The paintings on exhibit were of women's shoes, naturally.)

A few years ago Mr. Iolas learned of the gallery at No. 59 Corso Magenta. It occurred to him that it would be a marvelous idea to have Warhol create his own ``Last Supper'' and then display it across the street from Leonardo's masterpiece.

Warhol liked the idea, and started at first to make his ``Last Supper'' a truly contemporary work, envisioning Jesus as a hippy complete with earring and the locale for the feast a fast-food emporium, perhaps a MacDonald's or a Kentucky Fried Chicken spot. However, a more conservative approach seemed appropriate because this was a religious subject of some significance. And thus, the works on display evolved. How to see the exhibition

Perhaps the most interesting way to consider the show is in terms of a ``theme with variations'' (to borrow a term from music). Begin first with a visit to the Leonardo original in the Church of Santa Maria della Grazie, then simply step across the street to Palazzo delle Stelline to view variations by the most notorious, best-known pop artist of our era.

The show consists of 20 separate items, all based on Warhol's basic principle of repeated images (multiple prints of the same subject). An enlargement of a black and white newspaper photograph of Leonardo's original ``Last Supper'' serves as the basis for each of the works. Three of the pieces are huge canvases 10 feet tall by 40 feet long, with two silkscreen prints of the Leonardo photograph side by side. Each of these three is completely overlaid with translucent color: shocking pink, lemon yellow, and a complicated jigsaw design on the third painted in camouflage colors.

There are 12 relatively small canvases some 2 by 2 feet in size devoted just to the figure of Jesus, each of which has its own silkscreen pattern of overlaid colors in squares and rectangles. And finally, there are five canvases about three feet square, each of which contains two prints of the complete Leonardo work, one placed directly above the other on the canvas. Once more, each is completely covered with translucent colors: lemon yellow, shocking pink, apple green, and jigsaw puzzle patterns of camouflage colors.

Altogether, how does one evaluate such an exhibit?

The grainy, commercial texture and repetition of Leonardo's original fresco renders the image impassive, and therefore devoid of any value judgment. The choice of colors and the patterns of the overlays seem to have little relevance except for repetition. Similar to all Warhol shows, this one stimulates reactions alternating between bewilderment, suspicion, and reverence.

For those who wish to judge for themselves, the exhibit is open (free of charge) until March 21 (closed Sundays and Mondays, open other days 10 a.m. to 1 p.m. and 2:30 to 7 p.m.).