Visitors are staggering around the National Gallery of Art's East Building these days.

They're staggered first by the wonders of the finest collection of Aztec art ever assembled. Then they're staggered by the realization that half of these splendid objects were lovingly crafted to receive the tons of quivering human hearts and rivers of hot human blood that the Aztecs annually fed their gods.

The tension is immediate. At the entrance of the great hall crouches a monumental stone jaguar that, although carved from a block weighing many tons, seems about to spring lightly down from its step-pyramid pedestal. The viewer is drawn irresistibly closer and mounts the steps, and only then becomes aware of the great well in the beast's back, which was filled and refilled with sacrifices until the Spaniards came and put a bloody end to the bloody business.

Your eyes lift from this well of death to the wall opposite the entrance, where hangs the dedication plaque for the fifth and final rebuilding of the Templo Mayor of Tenochtitlan, which stood in what is now Mexico City. The stone is cunningly carved, the lines and masses and textures balanced by the eye and hand of some excellent artist. Decoded, the plaque tells us that the temple was finished in 1487, 32 years before Cortez led his Conquistadors ashore to destroy the mightiest empire in the Americas.

The Aztecs' shiploads of unsurpassed gold sculpture were melted into bullion; other artifacts that weren't destroyed were scattered around the world. The government of Mexico and two dozen museums and collectors cooperated to mount this exhibition, which isn't designed to be representative but to display the finest objects available.

And what the Aztecs were best at, it seems, was artful death.

They held a dedication ceremony for Templo Mayor that lasted from sunup to sundown for four straight days. During all those long days, without pause, young warriors were led to the altar, four at a time. Some went dancing and singing, some went kicking and screaming, but by the gods they went, rank on rank assembled. At the summit of the towering pyramid each was bent backward over the reeking stone and had his belly slashed open with a stone knife and saw his living heart held high by a priest. There were at least 10,600 sacrifices during the celebration and perhaps as many as 80,400. Split the difference, round it off, and that comes to around 22 tons of hearts.

Gallery officials have expressed the hope that we won't dwell on what these vessels were used for, but will appreciate them purely for their esthetics. "The Aztecs get a bad press," said H.B. (Nick) Nicholson, who was senior writer of the catalogue that accompanies the exhibition and is worth every dime of the $17.95 price. "The Spaniards regarded them as bloodthirsty savages, and that's pretty much been the lasting image. But the Aztecs believed their gods required the hearts and blood of young warriors or the sun and earth would die and the universe would come to an end.

"But they also loved music, and flowers, and family life. It was a cult of death, but the purpose was to sustain life."

Well, okay. The Aztecs took time to smell the flowers. They also held what they called "flower wars," in which neither side sought victory; the whole idea was to replenish the supply of sacrificial victims. The men who made captures acquired merit and promotions. The men who were captured acquired merit, too, because after they were sacrificed they went straight to heaven and joined the gods. It was the greatest of honors, the priests said, yet many of the honorees did not go gentle into that good night: Some were drugged, others were dragged.

Oh my. Here we are, dwelling on gore again, forgetting that half the 90 objets d'art here were not designed to facilitate the evisceration of men (and women and children -- always referred to as "beloved children" by the Aztecs -- who also were sacrificed as the occasion required).

Let us turn away from the jaguar heart tub and so forth and examine this funny- fearful sculpture of a crouching woman with a skull face. Hmmm. The caption says she's one of the Cihuateteo, the "goddesses" or "celestial princesses" into which the souls of women who died in childbirth were transformed. They escorted the sun from its zenith down the sky, taking over from the warriors who were slain in battle or sacrificed, who marched from dawn to noon. It was a great honor to die in childbirth.

If from time to time the princesses got tired of this day-out and day-out traipsing along with the sun, they could look forward to five days off a year. Where did they go on holiday? Well, they descended to the crossroads of the kingdom and hung out, hoping to kidnap young children.

Oh gosh, we seem to have lost the thread again. Let's turn to these lovely ceramic urns here, wonderfully incised with, let's have a squint, whoops: dismembered figures. The urns held ashes and bones, it says. Human? Of course. Well, what's this handsome stone box over here? Uh-oh, another reliquary. But the inhabitant may have died a natural death, which perhaps is why they put his ashes in a special box.

There, on the wall, a gold necklace that's a delight to the eyes. Until we focus in on the grinning skulls, with turquoise eyes and articulated jaws that tinkled merrily as the wearer moved. Don't let anybody tell you that the Aztecs didn't have a sense of fun.

Reeling right along, we come to a head that's a gleaming delight in polished greenstone. Only the skin doesn't seem to quite fit the face. Oh, now we see: It doesn't fit because it isn't his skin, it's somebody else's. This fellow is the god Xipe Totec (Flayed Our Lord), and in his honor, a penitent supplicant removed the skin, face and all, of an honoree who had just been relieved of his heart, and put it on like a skindiver's wetsuit. Might wear it for up to 20 days, it says, and the fringe benefits included relief of eye and skin ailments.

Well, that about wraps it up, except for some animal carvings there in the back. They're as graceful and skillful as any sculpture you'll ever see, and most of them are rattlesnakes. The Aztecs were fascinated by rattlesnakes, according to Elizabeth Boone of Dumbarton Oaks, which supplied many of the objects in and much of the expertise behind the exhibit. Does it surprise you to learn that the Aztecs were fascinated by rattlesnakes?

Most of the sculptures originally were brightly painted, but only a few retain traces of the pigment. Each was finished on all surfaces, including parts that never were expected to be seen again. After all, their slavering gods could see everywhere, and seemed at all times to be waiting for somebody to make some little mistake that only blood could wash away. Nicholson suggested that there's a parallel in Aztec sacred practice with the Christian Eucharist. The sacrifices were made "in a reverent spirit, with deep respect for the human body," he said.

This vast and benignant bloodletting went on for the two centuries during which the Aztecs rose from what Boone called "a miserable tribe of self-chosen people" to be masters of mesoamerica; they were wiped out in two years by the Spaniards, who appeared at the very time an Aztec myth predicted a light-skinned, bearded and angry god would come from the east.

Considered out of their context, these Aztec works are splendid. But it's hard, hard, to forget those who made such sacrifices for their art. ART OF AZTEC MEXICO -- Through January 8 at the East Building, National Gallery of Art.