National Pizza Day is Sunday. And sure, you’ve likely heard of the classic thin New York slice, or the saucy and rich Chicago deep dish (and the beef between their respective fans). But what about Omaha-style pizza, or a Grandma slice?

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There’s a lot more to pizza than the big cities would have you believe. Below are seven regional pizzas that you may have never heard of -- unless, of course, you live in the area.

Detroit style

Perhaps the most well-known of the unknown, Detroit-style pizza is baked in a deep, square pan -- not flat on a pizza pan. The result is a rectangular, thick pizza with a tall, chewy crust. The chewiness of the crust is also what is said to differentiate this style from other slices.

St. Louis style

Sure, St. Louis catches some flak for its unusual version of things (we’re looking at you, bagels). But the Midwestern state is undeterred in forging its own path -- like with its pizza, which is distinct because of its cracker-like crust typically made without yeast, and its rectangle slices.

Omaha style

This love-it-or-hate-it style starts with a yeast-free crust that has been described by the Omaha World-Herald as more of a biscuit than an authentic pizza dough. The flaky base -- which gets grilled during the cooking process -- is then topped with red sauce, mozzarella or Romano cheese (or a little of each) and a heaping helping of ground beef.

According to La Casa, the pizzeria credited with inventing the style, a true Omaha slice reportedly includes mushrooms and onions mixed with the beef.

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Grandma slice

Not to be confused with the (very similar) square Sicilian slice, which features a thicker crust and usually the cheese on top, a true Long Island Grandma pie is a square pizza that is layered with cheese first, followed by sauce on top. It is then -- like the Detroit-style pizza -- cooked in a rectangle pan until the crust is crispy. (For an even more authentic version, make sure it comes from an actual Italian grandmother.)

Cold Cheese pizza

Though the name might not sound all that appetizing -- unless you’re a cold pizza lover -- Cold Cheese pizza is probably not what you’re thinking.

The pizza style, which reportedly originated in Oneonta, N.Y., is not an actual cold slice of pizza. Instead, it’s a fresh, hot slice of pizza that is then topped with cold, shredded mozzarella cheese. The cult-favorite has since expanded to Pennsylvania and New Jersey.

Quad City style

Iowa and Illinois are coming in hot with what might be the most unique pizza of the regional styles.

Like many of those on this list, the difference comes down to the crust: Quad-City style uses a pizza crust made with malt. However, the idiosyncrasies of the rectangle slice don’t end there. The thin crust is then topped with a spicy sauce, usually made with red chili flakes, before the toppings are piled on, with the cheese on top.

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Ohio Valley style

Continuing on in the Midwest is the Ohio Valley-style pizza, which is almost a combination of many other styles featured on this list.

It starts as a square pie with thick crust that is then topped with sauce and cooked. Halfway through the bake, the pizza is removed from the oven, topped with more sauce and a thin layer of cheese and toppings, and then thrown back in. Once finished, the pizza is removed and topped with cold cheese. It is then served hot-and-cold.

Honorable Mention: Tomato Pie

While not exactly a pizza, Tomato Pie, also known as red bread, is close enough that it gets a mention.

Though there are many varieties of the Italian-American snack, the most authentic version hails from Philadelphia and is made using a thick, yet tender, bread that is then topped with an even thicker tomato sauce and then cut into squares.

Regardless of what region your pizza pie preferences lie, one thing is for sure -- Kiwi Pizza is apparently not acceptable.