From Argentina, Elayne Kramer astounds with a backbone as flexible as an archer’s bow! Photo by Bertrand Guay/Big Apple Circus

Audiences at the Big Apple Circus (BAC) may arrive at City Hall Plaza by newfangled contraptions like automobiles and the subway, but inside the sawdust-strewn ring the thrills and chuckles are strictly from the horse-and-buggy era.

“Legendarium,” a sonorous made-up word, is the title of the BAC’s 35th anniversary edition, which whisks spectators back to the earliest days of the circus in America.

Rosy-cheeked, bewhiskered John Kennedy Kane is the old-school ringmaster with a booming voice, proclaiming, “There is no smoking under the Big Top, but you are allowed to laugh, cheer and have a great time!” Between routines, Kane shares fascinating bits of circus lore like the story about New Yorkers who were hesitant to cross the newly built Brooklyn Bridge for fear it would collapse till a circus marched all 21 of its elephants across it with no problem.

After the charming opening charivari, (about which all we can say is you’ll have a cow when you see it), all eyes swivel aloft as the live band plays “The Daring Young Man on the Flying Trapeze” while Andrey Mantchev, a Bulgarian aerialist, clad in All-American red, white, and blue, gets the proceedings off to a heart-pounding start.

The good old days atmosphere is instantly evoked not only by the band’s nostalgic tune selections, but also by Mirena Rada’s sumptuous period costumes (including some bustles for the ladies).

But the real takes-you-back magic comes from the lighting by Broadway veteran Howell Binkley, designing his first BAC show. He has faux gaslights illuminating the ring and the crisscrossing spots piercing through the smoking-looking air to rivet attention on the facial expressions and amazing maneuvers of artists. Case in point: Argentine contortionist extraordinaire Elayne Kramer has many of the little girls wriggling in their seats trying to mimic her truly astounding convolutions.

“Legendarium” is so vintage that the troupe’s iconic clown Grandma (the now-retired Barry Lubin) was just a sweet young thing so she/he has been replaced by the Acrobuffos, a husband and bouncy-buttocked wife team, harkening back to the days before stage make-up when clowns wore commedia dell’arte masks instead.

Stealing the show (and audiences’ hearts) from these two cut-ups are the pound-rescued pooches in the second of two animal acts featuring trainer Jenny Vidbel. In a scene set in New York’s Central Park, her pack of ragtag canine rascals filch a choice morsel from a picnicker and leap fearlessly off ladders. Earlier in the evening Vidbel puts six gloriously groomed horses and six adorable white ponies through their paces.

This close-up experience has so many hard-to-believe-your-eyes routines that it’s impossible to pick just one favorite. Hailing from China are two cycling acts: Zhang Fan, a male unicyclist on the slack wire, and the Dalian Acrobatic Group, a team of seven female bicyclists decked out in various jockey silks.

For sheer novelty, it’s hard to top Emily and Menno van Dyke, who juggle Indian clubs while they’re tangled up dancing the tango! Or topsy-turvy Canadian Daniel Cyr on a dizzying roll inside the steel hoop he designed.

Performances continue through May 12. Details at bigapplecircus.org.