MEXICO CITY -- ''What," asked my guide, ''do you think the red color on this stone comes from?"
''Virgin sacrifice?" I piped up. After all, we were at Teotihuacan, the legendary archeological site about 30 miles outside Mexico City, a vast temple complex dedicated, at least according to some theories, to death.
''Wrong," the guide replied. ''It's from a cactus."
Nonetheless, there is enough evidence of morbidity at Teotihuacan to make it Halloween-worthy. Recent excavations have uncovered the bodies of warriors with their hands tied behind their backs, probably sacrifice victims. Both male and female sacrifices have been found at other locations on the site, which by around AD 600 had become the sixth largest city in the world, a thriving metropolis carefully planned around a central axis. In the center of the city is a museum, built in modern times, where funeral masks in clay and stone and elaborate burial urns are among the star objects.
Slowly, Teotihuacan itself died, to be rediscovered centuries later by the Aztecs who named the main road ''Avenue of the Dead," thinking that deceased rulers were buried under the various mounds along it. Eventually, though, the city became overgrown with vegetation. Only in the 20th century was it excavated, its majestic stone buildings revealed. The relief sculptures on their facades -- chiefly heads of snarling mythical beasts -- project two to three feet out from the walls, creating a dramatic, even threatening effect.
Allow yourself at least an entire day at Teotihuacan and wear sturdy walking shoes. You will need both to cover just the ''downtown" area of the city, with its huge stepped temples dedicated to the sun and moon.
Death seemed to stalk me all around Mexico City and its environs. Not that I ever felt in any personal danger. I only exercised the reasonable caution I would in any big city, and stayed out of the taxis that are green Volkswagens. Grasshopper in color, beetle in shape, they're are called ''The Kidnap Express" by the locals.
Death is an obsession here. There is the famous Day of the Dead, of course, in early November, when families decorate graves and welcome ancestral spirits back home. Considerable amounts of tequila, along with mariachi bands and fireworks, make the occasion more lively than grim.
Death is a prominent presence the rest of the year as well. It lurks in ancient ruined cities including Teotihuacan, and in contemporary art. The Mexico City artist Eduardo Abaroa uses skeleton imagery quite heavily in his work, and Teresa Margolles, also from Mexico City, has her studio in a morgue. She gathers the soapy wastewater from autopsies of unclaimed bodies and puts it into bubble machines that spew forth translucent orbs that float gently to the floor: She likes to think she is liberating the souls of those unidentified corpses.
Between Teotihuacan and Margolles comes the famous 20th-century muralist Diego Rivera. So fascinated with death was he that he collected the papier mache figures that were stand-ins for Judas and were traditionally burned on Easter. Rivera horded them instead. They are creepy presences in his home, which is now a museum. The building is in high modernist International style, a sculptural play of curves and angles in a posh suburban neighborhood near shops from Armani to Zegna. The metal hospital bed where Rivera died is still here, with his slippers and robe laid out on an embroidered bedspread.
Never one to think small, Rivera spent 10 years, from 1929--39, creating a vast mural cycle on ''The Epic of Mexico" in the courtyard of the Palacio Nacional, the country's official seat of government, located on the city's Main Square. The immense ''Epic" is all blood and gore, the story of a Latino Eden killed off by conquistadores who brought with them fatal diseases, syphilis and smallpox among them. Rivera painted officials of the Inquisition burning Mexicans at the stake or hanging them upside down. There is a happy ending: better living through communism.
On communism: It was Rivera who invited the Russian revolutionary leader Leon Trotsky, who had become Joseph Stalin's arch-enemy, to move to Mexico in 1937. In 1940, Trotsky survived an assassination attempt in his Mexico City house. Bullet-ridden walls testify to that incident. Afterward, an elaborate security system including watchtowers and alarms was put in place to protect him. But just months later, a man Trotsky had thought of as a disciple entered the house and hacked him to death with an ice pick.
Now a museum, the house is large and gloomy, filled with books, archives, old-fashioned black typewriters and telephones: It was as much a command center as a home. Trotsky's remains are in the garden; there's a hammer and sickle on his tombstone and a defiant red flag flying above.
Around the corner from Trotsky's house is that of a woman with similar political sympathies although she's far better known as a painter: Frida Kahlo. In addition to being Rivera's third wife, she was Trotsky's mistress. (While married, Kahlo and Rivera lived both together and apart, maintaining separate houses for their mutual convenience.)
Kahlo was born and died in this house that was owned by her family. Its bright blue color has helped make it a landmark, dubbed ''La Casa Azul." Even on a weekday there is a long line of people waiting to get in; after her death in 1954, Kahlo became a cult hero. The house is packed with art -- by herself, Rivera, European masters, and Mexican folk painters. Pictures of Mao and Stalin hang near indigenous crafts. A wheelchair and crutches are reminders of the horrific bus accident in her teens that left Kahlo a life of unrelenting pain. Death dominates many of her paintings: One portrays her with the sister and brother she never had; in another, she has a twin and the two share a single bleeding heart; another depicts the gore of a Caesarean section. Kahlo's ashes are here, in a pot in the form of a squatting female. Among her keepsakes is a display of butterflies, mounted and framed, symbols of freedom stifled -- as hers was.
The Dolores Olmedo Patino Museum, on a grandly restored estate on the fringes of the city, is yet another complex filled with work by Kahlo and Rivera, in addition to a great deal of other Mexican art. Patino and Rivera were lovers. She was rich: Among the museum's holdings is the 365-piece sterling silver service that the French company Christofle made for Maximilian, the much-despised ruler whose fate is so dramatically depicted in Manet's painting ''The Execution of the Emperor Maximilian."
Ironically, Patino's collections demonstrate that while Rivera was emulating Cezanne, Cubism, and other European masters and movements, Kahlo was a true original whose autobiography in paint is first-rate. She seems to turn herself inside out in her tormented images.
There are tormented images galore in Mexico City's National Anthropology Museum, which was an easy walk from my hotel, the Presidente Intercontinental, where you can drink the purified water but might want to opt for wine. The Presidente lays claim to the most illustrious wine cellar in all of Latin America, and boasts an array of restaurants that stand up to every vintage.
No macabre experiences at the hotel. The Anthropology Museum, though, is rife with them. There's evidence of ritual cannibalism practiced in preclassic times, when the average lifespan was 26 years. Specialists can identify cannibalism from the way the victim's bones were cut, in order to reach the nutrient-rich marrow. Figures of ocelots in the museum have cavities in their backs, to hold the blood and hearts of captive warriors. And so on.
Like Teotihuacan, the Anthropology Museum is worth an entire day. And if you are lucky, when you exit you will be treated to ''La Danza del Volador" in the park across the street. An elaborate rite with different meanings among different indigenous peoples, this version is touristy. Four men each hang by one foot, upside down, from the top of a tall pole. As they swing around, the ropes holding them gradually unfurl so these daredevils get lower and lower, until they seem about to crash their craniums into the cement. It's a Maypole dance -- but turned into a near-death experience.