Which of these 32 beloved Pittsburgh pizza parlors should make the Sweet Sixteen? And what is Pittsburgh-style pizza anyway?

Update, Nov. 10: Introducing the Ultimate Pittsburgh Pizza Champion: Vincent’s Pizza Park

Update, Oct. 28: Vote for the Ultimate Pittsburgh Pizza bracket champion

Update, Oct. 21: Final Four: Vote to show your love for Pittsburgh’s Ultimate Pizza

Update, Oct. 14: Elite Eight: Vote in the Ultimate Pittsburgh Pizza bracket

Update, Oct. 7: Sweet Sixteen: Vote in the Ultimate Pittsburgh Pizza bracket

Fifty-nine years ago Friday, Frank Aloe at Frank’s Pizzeria in Ambridge gave away slices of pizza on the restaurant’s opening day.

“That was in 1958, and the rest, they say, was history,” Robert Aloe, business partner, said. “The pizza was free the first night because he wanted people to try it and see if they liked it, and I guess they did because we’re here 59 years later.”

The story is just one of the many origin stories of Pittsburgh pizza shops — and in Pittsburgh, different types of pizza are abundant. That means defining what makes a “Pittsburgh-style pizza” can be tough.

“You could go to a place like Il Pizzaiolo or Piccolo Forno and have pizza that would be more similar to what you would experience in Italy, that Neopolitan pizza. Then you have Mineo’s and Aiello’s that are your family-run pizza parlors where you have that neighborhood rivalry. Then you have your real thin-crust New York-style, which you see at Spak Brothers,” Melissa E. Marinaro, director of the Italian American Program at Heinz History Center, said. “It all goes to where are you training, where are you learning the skill.”

In Pittsburgh, Italian immigrants settled throughout the city, not just in Bloomfield, Pittsburgh’s Little Italy.

“There were enclaves all throughout the city — South Oakland, Squirrel Hill, the Lower Hill, Mount Washington, Beltzhoover,” Marinaro said. “Each settlement is often reflective of different parts of Italy.”

And that means there are different types of pizza throughout the city, as well.

“There will be different Italian food. You can kind of tell where the family’s origins would be from in Italy,” she said. “If you start to look into the ingredients as a person who’s into food, you can start to suss out where these families have their origins.”

So perhaps Pittsburgh pizza isn’t defined as a single type, the way Detroit pizza and New York pizza and Chicago pizza are. Instead, it’s defined by its variety.

“Pizza shops are one of those few restaurants that don’t have the same fail rate as other new restaurants because your ingredients are cheaper, and it means your production costs will be less expensive,” she said. “Nowadays, you have [pizza] chains owned by Turkish families, other new immigrants.”

For Frank Aloe, a pizza shop was the business that stuck. Robert Aloe said his late father worked in a local steel mill, after immigrating to Pittsburgh with his wife, Costanza, after they married in Calabria. But work at the mill was inconsistent, and they wanted a second form of income. They tried to open a fish market, but it closed. Then, they tried an Italian pastry shop, but that closed, as well.

Then, he picked up an Italian newspaper called Il Progresso and spotted an ad that caught his attention: For just $600, go to New York City and learn to make pizza and take home all the equipment you’ll need to run a pizza shop. He left for New York and learned to make the shop’s beloved cheese-under-the-sauce pizza.

Frank Aloe’s work is sealed into history at the Heinz History Center. Aloe’s original pizza peel is on display there.

“You could still smell the pizza on the peel when it came into the museum,” Marinaro said.

The New York pizza trip taught Aloe to make the cheese-on-the-bottom recipe ensures that the cheese won’t fall off and won’t burn. Costanza Aloe still works in the shop every night, making pizza and her famed calzones.

Frank’s Pizzeria has been in the same location since the beginning, and it’s adapted to customers’ needs, changing shop hours based on customer demand. (To be clear, the Frank’s pizza on our bracket is a different Frank. Frank’s Pizzeria just missed the cut.)

To Aloe, he’s not sure there is an exact type of Pittsburgh pizza.

“To say there is an exact Pittsburgh pizza, I can’t say there is, but what I’ve noticed is a lot of Beaver County pizzas are square and Allegheny County pizza is round,” he said. “I don’t know why the distinction but that just seems to be.”

Vote for the Ultimate Pittsburgh Pizza

We think you can define “Pittsburgh-style pizza” by whatever is your favorite slice, so we want to know: What is the Ultimate Pittsburgh Pizza?

So to do that, we went to the experts: All of you. You nominated hundreds of the city’s and suburbs’ beloved pizza parlors. We crunched the data to see which shops got the most votes and then checked that against reviews and our expert opinions to seed a list of 32 contenders, which will now face off in an NCAA-style bracket.

We’ll whittle down the options each week based on your votes, so be sure to come back and vote your favorite parlor to the top.

Now’s your moment to shine a spotlight on your favorite Pittsburgh pizza. Vote below or here by 10 a.m. Oct 4.