How a misunderstanding made a Miami city

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Soaring white columns of sleek white rock flank the entrance to the Coral Gables Art Cinema. Along Aragon Avenue, fossilized corals form a textured grey rock wall. Concrete street signs mimicking the limestone rest at the base of each street, forcing navigators to look down to find their way. The entire city of Coral Gables seems artistically inspired by the natural world beneath the surface, in the waters around and just below.

And it all started with one house.

In 1899, when Althea Fink Merrick moved to Miami with her family, sight unseen, she arrived at her new home to find that it was little more than a wooden shack surrounded by scattered guava trees. With no money to go back, she focused instead on building anew.

But in a city with no natural brick, building a sturdy house was a challenge.

So Merrick turned to oolitic limestone, a smooth sedimentary rock mined from nearby quarries. It gave the house’s exterior an unusual, textured pattern, but it was strong, and stately in its own way.

The gabled roof mirrored the Massachusetts summer home of former president Grover Cleveland. (A gabled roof is designed with two sloping sides meeting in the middle at a gable, which is a triangle. Imagine a typical child’s drawing of a house.)


She designed a home that blended her new life in South Florida and her roots in New England. The house, with the gabled roof and limestone walls — which they wrongly thought was coral — came to be called “Coral Gables.”

Years later, her son George Merrick went on to design the rest of the area in a similar style, naming the city after the house he grew up in.

But the city’s name is a bit misleading. Most of what we think of as coral in the Gables is actually an oolitic limestone, according to Colin Foord, a marine biologist and co-founder of Coral Morphologic, an arts and education organization focused on coral.

Oolitic limestone like the one used on the Merrick House is made up of millions of tiny little spheres of calcium carbonate called oolites. The calcium carbonate comes from lots of different things, but usually is an accumulation of pieces of shells, corals, algae, and fecal debris. It can also be formed from precipitation.

Much of the construction back then was done with this material because there was no other rock found locally, according to Foord. It was also perfect for the Mediterranean style Merrick envisioned for the area’s two-story homes with pitched roofs and textured walls.

How it works

So how do you build with limestone? Well, it starts at a quarry, which are large mounds of limestone that have accumulated over thousands of years. Excavators take a giant circular saw, about six feet in diameter, and cut out big blocks of limestone that weigh about a ton each, according to Dr. Eugene Shinn, a retired research geologist with the U.S. Geological Survey Center for Coastal Geology in St. Petersburg.

Then these limestone bricks are layered one on top of the other and sealed with cement — which is also made by heating up limestone and mixing it with a few other ingredients.

Buildings like the Merrick House, Coral Gables Art Cinema, Books and Books, and the Coral Gables Museum used some limestone quarried from what is now the Venetian Pool. In the early 1900s the pool wasn’t a pool at all — it was a mound of limestone. After it was excavated, water flooded in and turned it into the frigid but beautiful swimming hole it is today.

That process repeated itself across Miami-Dade — many of the small lakes and canals dotting the Gables and other parts of Dade originated as quarries. New ones are still cropping up today, says Foord. Now, the areas around those quarry-turned-lakes are valuable residential waterfront property.

The coral in Coral Gables

Actual coral is used sparingly, and usually only as a decorative facade because it’s so expensive. The Coral Gables Museum, which began as the fire and police station, is one of the few buildings that uses it. The coral-containing limestone rock covering the walls, known as Keystone, was quarried at Windley Key in the Florida Keys.

And it spread throughout the county. When it came time to build the David W. Dyer Federal Building and U.S. Courthouse, designers took inspiration from the Gables and used this Keystone to decorate the walls of the iconic building in Downtown.

Along the walls of the museum and the courthouse, you’ll see brain corals, whose name comes from the way it resembles a cross-section of a human brain. You’ll also find star coral, which looks like a series of little circles randomly pressed next to each other.

And it’s not just on the buildings.

“Both of those are species that are still alive today, so even though in architecture you see them as fossils, this Key Largo Keystone are still alive and are on average 120,000 years old,” Foord said.

If you dive off the coast of the Florida Keys, it might not look so unfamiliar, because families of these corals that now adorn the walls of Coral Gables live, breath, and similarly decorate an entire world in the water just below.