Hundreds of fantastic mythical surreal paper mache creations called ‘Alebrijes’ fill the Zocalo, the grand central plaza in the heart of Mexico City, during Mexico's Day of the Dead celebrations. (William Booth/WASHINGTON POST)

Once upon a time, it was the Day of the Dead, but now it is the days of the dead.

A reverent, rural tradition of making picnics at the cemetery, of building a home altar of marigolds for the dearly departed? That continues.

But like Halloween in the United States, Dia de los Muertes in Mexico has become a bit of a free-for-all, a five-day weekend with parties and drinking, a smash-up where dad dons a Spider Man costume and mom dresses up as a naughty French maid — to honor their ancestors, of course. It’s more pop, more pagan and more commercial. There’s even some trick or treating, which would have been unheard of a decade ago.

Along with the national holiday vibe in the capital — and sales of sugar skulls and votive candles — comes the world’s largest display of folk art animals called “alebrijes,” fantastic creatures with claws and wings and tails, the surreal made real with chicken wire and paper mache.

These animals of whimsy are traditionally carved out of small pieces of copal wood and placed on the shelves of uncounted curio stalls — but these alebrijes are made of cardboard and they are huge.

For the past five years, the Museum of Popular Art in Mexico City has staged a contest, a parade and display of hundreds of the towering beasts. They began appearing a few weeks ago on Paseo de Reforma, the city’s premier avenue, and on Sunday before dawn they were moved to the central plaza, the Zocalo, the Aztec heart of the city now ringed by the old national palace, cathedral and city hall.

As the sun was rising Sunday to greet the street sweepers and the previous night’s revelers, the early morning joggers and police were there when the first tour buses arrived, and visitors spilled out onto the plaza to gawk.

Pedro Rivas, 22, an assistant for a clothes designer, said the creatures looked like something from a drug trip. “But a good one, like a cartoon.” Alexis Cardenas, 33, a waiter, watched his children run around the sculptures, laughing. “They’re crazy, these animals, like Mexico. We pretend to be very formal, but we’re romantic. We love this kind of thing.”

Some of the creatures look like escapees from the H.G. Wells science-fiction classic, “The Island of Doctor Moreau” — such as an octopus lizard pig with talons and a whale’s tail; or a fever dream of Salvador Dali meeting the Cat in the Hat, painted in the bright swirling blues and scaled greens of Mexico’s southern state of Oaxaca, where the folk art form was born.

More than 2 million people will see this year’s menagerie.

“There is a great tradition of fantastic animals around the world,” said Luis Armando Haza, a director at the Museum of Popular Art. “The Asian cultures have their dragons, the Irish their gnomes, in Norway, they have trolls? But the difference for the Mexican alebrijes is the colors of southeast Mexico.”

Haza said that most of the creatures in the Zocalo have three things in common: wings, claws and tails. “The tail is for defense, and the claw is to catch their prey and hold them to the earth, and wings remind us that we all have dreams and can fly away,” Haza said.

Ricardo Linares, a sculptor and art historian whose family workshop produces prized, collectible alebrijes, recalled a parade a few years ago, when it rained. “It melted half of them. It looked like a cemetery of alebrijes!” Linares said.

While most visitors downtown expect to see the mythical creatures arise in the Zocalo around the time of the Day of the Dead celebrations, Linares said they belong to different traditions.

“Each person has an animal counterpart and every day, our moods, our natures are changing, so we are not just one animal but a mix of animals, and that everything is always shifting, cultures, people, societies, and that all of the shapes and colors, the extreme and terrible and beautiful, can coexist and make us more beautiful,” Linares said.

What will happen to the sculptures after the public exhibit ends? Some of the sponsors may take them to their homes or offices, but because of the fragile material, the creatures only survive for a few years.

Usually, the artists destroy them.

“They go into the recycling bin,” Haza said, to be born again.

Researcher Gabriela Martinez contributed to this report