Bodybuilding broke into the mainstream during the sport’s so-called “Golden Era”—a time when icons like Frank Zane, Lee Haney, and Arnold Schwarzenegger competed on the Olympia stage with aesthetically minded physiques that put a premium on size, symmetry, and a certain grace and fluidity. That was all well and good for the ‘60s, ‘70s, and ‘80s, but the 1990s was a completely different world.

This was a time when all athletes—ranging from professional wrestlers to baseball players—began to grow to Olympia proportions. So it only made sense for the bodybuilders themselves to get—well—even bigger than that. Broader shoulders, barrel chests, pants-splitting quads, and scales tipping well over 270-300 (sometimes even more!) pounds became a necessity for anyone with dreams of a Sandow.

Thus began the era of the “Mass Monster,” and while there’s no clear starting point to the trend, you can begin with the rise of Dorian Yates, whose hulking frame led to an Olympia dynasty in the early ’90s, coming right after that of Lee Haney, one of the most aesthetic of all the classic “Golden Age” competitors. It was a changing of the guard for the entire world of bodybuilding, where pleasing aesthetics gave way to jaw-dropping size—and if you wanted to win, you needed plenty of mass to go around.

While the art of bodybuilding is always at the forefront of the sport, there’s nothing wrong with gazing in awe at some of the freakish physiques that came from the “Mass Monster” era—an era that still influences bodybuilding stages today.