The longest theatrical experiment in recent memory is officially underway. Last Thursday night, Taylor Mac, a gender-bending, freewheeling and critical-minded performance artist, debuted the first act of “A 24-Decade History of Popular Music,” his 24-hour, decade by decade exploration of American song and culture from 1776 through 2016, at St. Ann’s Warehouse in downtown Brooklyn.

On Oct. 8 beginning at noon, Mac will perform the entire opus from start to finish over 24 consecutive hours. But in the meanwhile, he is performing a different three-hour installment every few days. He performed 1776 to 1806 on Thursday and continued with 1806 to 1836 on Saturday.

Mac focuses each decade on a different historical theme or event (i.e. the Revolutionary War, the temperance movement, the Trail of Tears) using fanciful storytelling, personal anecdotes and songs from the time (which have so far included patriotic anthems, folk songs and antique ballads). He is joined by a full-size orchestra (which will slowly dwindle in size) and a chorus of assistants.

Audience members are free to take bathroom breaks, but Mac takes no intermission. Once each hourlong segment ends, he quickly changes into a new equally elaborate and outrageous wardrobe and headdress (designed by Machine Dazzle) and emerges anew, still full of energy.

Audience members may feel uncomfortable with the numerous acts of mass participation, which have so far included sitting on the floor, getting pulled onstage, wearing blindfolds, singing, sharing personal memories, and numerous other physical activities. But Mac doesn’t seem to mind. “Everything you’re feeling is appropriate,” he says more than once.

The 24-hour performance is probably only meant for Mac’s biggest fans, but anyone who appreciates wild and crazy theater, cabaret and/or performance art is strongly encouraged to check out at least one installment of this unforgettable set of history lessons.