NEW YORK -- The Big Apple is facing south these days, with 30 museums and galleries serving up a visual feast of Mexican art. All around the city, different facets of it are on exhibit, from ancient masks to contemporary photography, turning Manhattan into a multimedia Mexican festival.

In terms of sheer tonnage, however, the Metropolitan Museum's "Mexico -- Splendors of Thirty Centuries" is the biggest attraction and a crushing success. The volume alone of exotic objects, executed in gold, jade, ceramic, obsidian, feathers, volcanic stone and plain oil on canvas, represents a staggering number of treasures. With more than 400 works of art in 25 galleries, the exhibition is easily the museum's largest, bigger than "India!" mounted by the Met in 1985 with similar hoopla. An equally heavy 728-page catalogue, highlighted by Nobel Prize winner Octavio Paz's essay "The Will to Form," carves poetic sense out of this overwhelming cornucopia of images.

If there is a thread that ties together the centuries of accumulated art history in this exhibition, it is a bloody one, from the 9th-century "Chacmool" sculpture of the Mayas, holding an ominous stone plate for sacrificed human hearts, to Frida Kahlo's haunting surrealism of the 20th century.

The "chacmool," a generic name for the half-sitting, half-lying human figures that abound at the Mayan ruins of Chichen Itza and later adopted by the Aztecs in their capital city of Tenochtitlan, could be a forebear of Henry Moore. It is coiffed in a boxlike headdress and further adorned with carved ear spools, nose buttons and a double-strand necklace supporting a pendant in the form of a human face. The label gingerly explains that the chacmools served as "recipients of sacrificial offerings within specific sanctuary contexts."

Pre-Columbian objects culled from eight distinct archaeological sites overpower -- on an aesthetic plane -- the impending invasion of post-Conquest art, begun with the victory of Cortes over the Aztec king, Montezuma in 1519. Appropriately, the floor of this vast pre-Conquest section is bare stone, as if to accommodate the ceaseless flowing of sacrificial blood. The rest of the galleries are carpeted. There is no end to this impression of strangeness, whether it's in the form of the colossal Olmec head carved out of basalt from 1,000 B.C. that first greets you in the museum's Great Hall, or the nine-inch-high ceramic animal vessel, probably from Teotihuacan, crouching and playing a flute.

Three-quarters of the objects are from Mexican collections, museums or churches and rarely travel. The rest -- including the animal vessel -- were borrowed from American or European collections with many of them bearing labels of "provenance unknown." They were, for the most part, snatched at one point from their archaeological "find spots" and spirited out of Mexico.

Much of Mexico's cultural patrimony is scattered in the permanent collections of prestigious foreign museums, from the Hermitage to the Vatican. And it is still hard to imagine how a private American collector could own even a fragment of the spectacular painted lime plaster fresco that once decorated a wall near the great stepped pyramids at Teotihuacan, but he did and here it is.

The processional figure in a tassel headdress "speaks" with a flowered sound scroll unrolling from his opened mouth. In front of him stands a smaller figure representing a storm god with curved fangs. Drops of blood fall from his mouth, signifying human sacrifice. The viceregal -- "colonial" is a term avoided in this show -- era takes over with the impressive mounted figure of "Saint James the Moor-Killer" who would be more aptly titled "mataindios," or "Indian-killer," in this context. He is a fabulous figure, polychromed in wood armor and much more convincing than the nearby folding-screen painting depicting the famous meeting between Cortes and Montezuma. Cortes' chronicler, Bernal Diaz del Castillo, witnessed the historic encounter: " ... the great Montezuma descended from his litter ... beneath a marvelously rich canopy of green feathers decorated with gold work, silver, pearls and jade."

The Spaniards built their Christian cathedrals over the ruins of sacred Indian sites and the wildly disparate cultures churned out a new version of the renaissance. Great European artists like Durer and Cellini praised the Aztec and Mayan "exotica" that traveled there but it was primarily a one-way passage. Mexico became Europeanized and, as one might guess, the imprimatur of spilled blood segued effortlessly into the gory lore of Christian saints.

"St. Lucy," the virgin martyr, does not simply display her gouged-out eyes on a plate as one finds depicted in the north. Here the sculptor provides the beautiful martyr with a dagger, and the blood flows freely from her right eye socket. Some of these 16th-to-18th-century works approach the kitsch as if Jeff Koons had received a commission from the church. "St. Christopher and the Christ Child" is one amazing example. The grossly baroque, 94 1/2-inch-high giant staggers under the weight of the Christ child.

The kitsch aspect -- the daunting expanses of silver and gold reliquaries and chalices and formidable wave of accomplished but ultimately dull 19th-century academic painting -- is relieved by show-stopping masterworks. "San Felipe de Jesus," a 17th-century gilded and polychromed wood sculpture of the martyred saint is normally revered in Mexico City's majestic Catedral Metropolitana. His floral-pattern habit is convincingly pierced by two lances in an X-shape thrust that impales him in space and a third wound is visible above his heart. His expressive gaze, outstretched arms and deathly pallor are both dazzling and moving.

The compelling late 17th-century portrait of the intellectual, poet and Catholic nun Sor Juana Ines de la Cruz poised in front of her library, quill pen in hand, could easily escape attention in a demanding exhibition of this magnitude. But it is worth special attention, in part because of who she was. Paz considers Sor Juana "the first feminist in this country" with no literary equal until the arrival of Emily Dickinson. It's an example of how, with so many strange and wonderful objects and paintings in this exhibit, the more subtle -- or at first glance -- ordinary, suffers.

"Depictions of Racial Mixture" by Miguel Cabrera is one such spot, illuminating the growing country's obsession with blood lines. Cabrera was considered the most popular Mexican painter of the 18th century and was a mestizo himself. Like an exotic still life, each of the three paintings depicts a mother, father and child, exhibiting various infusions of white, black and Indian blood. Cabrera's work pales in comparison to the rougher, folklike paintings of Hermenegildo Bustos, whose penetrating self-portrait on metal from 1891 is fiercely brilliant and free of any academic strain.

Equally unique are the biting broadsides of Jose Guadalupe Posado, Mexico's Hogarth. It is the selection of 20th-century painters -- the familiar names of the Mexican muralistas Orozco, Rivera and Siqueros -- that carries the exhibit to mid-century. They are represented by easel paintings for obvious reasons. This last section abruptly ends with Rufino Tamayo -- ignoring all dialogue with Mexico's contemporary artists.

These last galleries are dominated by the painterly aura of Frida Kahlo, Rivera's wife and onetime lover of Trotsky. Kahlo died in 1954 but she remains a larger-than-life star with million-dollar-plus price tags for her wounded self-portraits. There are droves of admirers here at the Met and farther uptown at the National Academy of Design, where nine more of her paintings are on view.

Kahlo's "Self-Portrait With Monkeys," from 1943, continues the silky web of Aztec roots. Monkeys symbolized lust in that culture. The furry creatures surrounding and embracing her are as strange in this setting as the part-animal, part human stone sculptures of the Zapotecs from Monte Alban on view at the opposite end of the exhibition hall. Sponsored by the Los Angeles-based Friends of the Arts of Mexico, a private foundation of Mexican corporations and "American friends," the multimillion dollar show will close here Jan. 13th and then travel to the San Antonio Museum of Art (April 6-Aug. 4, 1991) and the Los Angeles County Museum of Art (Oct. 6-Dec. 29, 1991). The effort is truly Herculean, and few institutions could pull off such an ambitious undertaking.

The Metropolitan show is in many ways a larger and more scholarly remake of the Museum of Modern Art's "Twenty Centuries of Mexican Art/Vente Siglos de Arte Mexicano" that opened in 1940, also in collaboration with the Mexican government. This time around, however, all of the funding is private. The passing of 50 years has not done much for Mexico's international image and this sleek masterwork of cultural diplomacy will expand the public's narrow awareness of Mexico's true riches.