When acclaimed Sarasota architect Tim Seibert remodeled a then-unremarkable house on Siesta Key in 1971, he dressed up the home with a lacelike curtain of mid-century modern breeze blocks along its western wall. The breeze blocks—concrete structures crafted in geometrically appealing shapes and patterns that facilitate the flow of air and outside views from inside the home—made the house cool, style-wise.

The grillage, which Seibert says added “texture and the look of a modern building” to the Ness House (named for its original owner), became an icon of the Sarasota School of Architecture’s forward-thinking style. More than decorative, breeze blocks serve a functional purpose, which embodies the school’s principle that inside and outside should interact: They filter sunlight and bring breezes into the interior of an abode while affording a view of the yard from indoors. These concrete snowflakes peaked in popularity during the 1950s and 1960s, before central air-conditioning was the norm, particularly in the hottest parts of the U.S., like Florida. The concept of a permeable wall dates back centuries earlier to warm parts of southern Europe like Spain and Portugal, as well as the Middle East. “When Europeans came to the New World, they brought that idea with them,” Seibert says.

Breeze blocks remain a common sight in Florida, where they are found on both vintage buildings and new construction. Today, three Florida companies manufacture the fashionable fixtures: A-1 Block Corporation in Orlando, Carroll’s Building Materials in St. Petersburg and White Cement Specialties in Venice.

“They’re fun-loving, not totally serious, and just give buildings a whole lot of texture and look,” says Janet Minker, board chair of the Sarasota Architectural Foundation. “Mid-century modern is very en vogue.”

Everyone who’s owned the sleek Ness House agrees that the stacked aerated cement has a lasting, classic coolness. Forty-five years and at least two additional remodels after the original renovation, the blocks still stand.