I went to the 85-year-old restaurant that taught Taco Bell's creator how to make its iconic taco and it shows just how much the chain has evolved in 5 decades

If it weren't for the steady stream of customers walking from a nearby parking lot, I wouldn't have known that Mitla Cafe was even open.

Despite the triple distinction of being located along historic Route 66, being open for 85 years, and being the foundation for the popularization of tacos nationwide, there's no signage on the outside of Mitla Cafe touting as much.

Growing up in the suburban northeastern US, Mitla Cafe immediately felt familiar — like so many Italian-American restaurants I frequented as a child.

Photos of family and friends hang on every wall as a testament to the four generations of the same family that continues to own and operate the decades-old restaurant.

A single 8.5 x 11 piece of paper — pinned to the community cork board alongside a half dozen business cards and an advertisement for amateur Lucha Libre — is the only indication in Mitla Cafe that there is any connection to Glen Bell and the Taco Bell fast-food franchise.

Despite being in the restaurant explicitly because of its history, I didn't even notice the paper until a family relative who happened to be in the restaurant picking up food saw me snapping photos and asked if I knew of the connection to Taco Bell.

In Gustavo Arellano's foundational food history book "Taco USA: How Mexican Food Conquered America," the author documents how Bell — who owned nearby Bell's Burgers, and later founded Taco Bell — learned how to make tacos.

"He used to come over here all the time," Irma Montaño, a descendent of the original owners Lucia Rodriguez and Vicente Montaño, told Arellano. "My father-in-law would say Mr. Bell kept asking about the tacos, how he made them, and so my father-in-law finally invited him into the kitchen to teach him."

When asked about the history, the current owners of Mitla Cafe demur.

"Everyone's been fairly philosophical," current co-owner Mike Montaño told CBS last November. "I don't want people to feel like they weren't successful or that they were taken advantage of or anything like that."

Irma Montaño was similarly positive in Arellano's book. "Good for him," she said. "He was a self-starter, and he did push those tacos."

Taco Bell representatives didn't respond to a request for comment regarding the company's history page excluding Mitla Cafe and the Montaño family.

Regardless of its history, Mitla Cafe wasn't packed full of tourists roadtripping along Route 66. Instead, both the dining room and the bar area were full of locals. I was certainly the only guy in the dining room furiously snapping photos of my food.

There's a "Mexican Combinations" section and an "American Flavor" section on Mitla Cafe's menu — an anachronistic nod to a previous era, when Mexican food like tacos and enchiladas weren't considered as American as apple pie.

You can order an "orange whip" to drink — a drink that was last in style decades deep into the previous century.

There's not even an obvious way to order the hard-shelled ground beef taco that Mitla is famous for having created. Among the 31 items listed under the "A La Carte" section is one simply labeled "Taco." It is there that you can specify "hard-shelled" and "ground beef."

You can see the difference both in the tortilla's lighter color and in the irregularity of its edges. You can also instantly taste the difference, as Mitla's hard-shelled tortilla doesn't instantly crack into a trillion pieces after a single bite.

The biggest difference in flavor comes from the primary ingredient in Mitla Cafe's hard-shelled taco: The beef.

Rather than using loosely sauteed beef which can sog through the tortilla, Mitla creates a kind of burger patty. It's heavily-spiced, textured, and wildly delicious. The beef, beyond everything else, was the best part of Mitla's foundational taco.

It probably goes without saying, but this is a significantly better taco than the one it inspired at Taco Bell.

More often than not, the lettuce and tomatoes used in fast food items is limp, cold, and flavorless. That's because it's often pre-cut and shipped in bags to the franchise for ease of use.

The experience at Mitla Cafe was what you would expect from a restaurant: the lettuce and tomato were crisp, and the cheddar was room temperature rather than cold. We're not talking about a revelatory experience here, but it's clear that the quality was higher solely based on its context. And it makes a difference in the final product when you're biting through crunchy lettuce rather than wilted greens.

From the fast, friendly service to the delicious food, it's easy to understand why Mitla Cafe has survived and thrived for nearly 100 years.

For me, having grown up in the suburbs outside New York City, the experience at Mitla Cafe evoked nostalgia-laced memories of chicken cacciatore and lasagna dinners at my favorite Italian-American restaurant from childhood, John the Baker. The flavors are different, of course, but there's a universality to comforting home cooking that crosses cultures seamlessly.