Rome is such a popular tourist destination that many know quite a bit about the capital of Italy. But even if you've toured the Colosseum and tossed a coin in the Trevi Fountain, it's safe to say you don't know all there is to know about Rome. From misnomers to missed World Fairs, here are 10 things you likely never knew about Rome.

Cats Are Revered and a Protected Species in Rome

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It's no secret that cats are beloved in this historic city. In his book Call of the Cats: What I Learned About Life and Love From a Feral Colony, Andrew Bloomfield highlights Italy's bio-cultural heritage laws that protect felines in Rome. The laws state that five or more cats living in urban habitats cannot be exiled from their homes — ever.

In 2001, the city named the cats living in the Forum, Colosseum, and Largo di Torre Argentina as part of Rome's bio-heritage. Today, hundreds of cats make their home among the temple ruins of the Largo di Torre Argentina at an on-site cat sanctuary.

Its Main Road Is More Than 2,300 Years Old

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Construction on the Via Appia, the primary road through the center of Rome, began in mid-fourth century B.C. At its peak, the road ran 560 kilometers from Rome to Brindisi, a southern port city on the heel of the Italian boot.

Today, you can still walk much of the Via Appia in Rome and traverse the Appia Antica Regional Park, along which you'll see a myriad of tombs from ancient days.

The Spanish Steps Aren't Spanish

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The famous staircase, which connects the Piazza di Spagna with the Trinità dei Monti church in central Rome, was actually designed by an Italian in 1725. Consisting of 135 steps, it got its name from the Spanish Embassy located on the square below.

If you're headed to Rome anytime soon, don't expect to lounge on the Spanish Steps with gelato in hand; the city has recently banned sitting on the steps in an effort to preserve their structural integrity. Visitors who ignore the warnings of patrolling officers could be subject to fines of up to 400 euros.

It Almost Hosted the 1942 World's Fair

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The keyword here is "almost." Benito Mussolini, the Italian prime minister from 1922 to 1943, intended the fair to be a celebration of the Roman Empire's legendary status and Italy's rise under fascism.

The outbreak of World War II saw the cancellation of the 1942 Expo, but not before an entire Roman district was augmented with Fascist-style architecture in preparation for the event. Today, the EUR neighborhood — named after the scheduled "Esposizione Universale di Roma" — still proffers a somewhat dystopian aura, with its marbled geometric buildings and rationalist architectural elements, despite never having been used for its intended purpose.

It Wasn't Always the Capital of Italy

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While the rest of the Italian states were unified under the Kingdom of Italy in 1861, Rome remained under papal rule. It was Turin that was first chosen as the new country's capital, an honor that was later conferred on Florence in 1865. It wasn't until the Italian army took control of Rome from the papal troops in 1870 that the city became the country's capital.

Vatican City, which lies entirely within Rome's boundaries, has remained separate. The 1929 Lateran Treaty recognized both the state of Italy and its Roman capital, as well as the sovereignty of the pope within the Vatican.

It Is Home to the Largest University in Europe

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The University of Rome, known as La Sapienza, was founded in 1303, making it one of the oldest universities in the world. Today, with approximately 112,000 students, it's the largest university in Europe.

Originally founded by Pope Boniface VIII, the school has at times suffered tumultuous relations with the Catholic church. It was closed in 1527 for the entirety of Clement VII's papacy. However, it has flourished in recent decades and currently hosts more than 140,000 students from all over the world.

The Romans Invented a Precursor to Modern Cement

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Though various other building techniques were utilized worldwide, the Romans were the first to use anything resembling our modern cement in large-scale construction projects. It was this sort of innovative spirit that led the Romans to build the Pantheon, which was completed in A.D. 125 and is still the largest non-reinforced concrete dome ever built.

Why do we see cracks in our concrete sidewalks within decades, while Roman structures from over a thousand years ago stand unscathed? The secret is in the recipe: scientists have discovered that the Roman technique of combining seawater and volcanic ash produces a rare mineral in the concrete. This mineral, called aluminum tobermorite, strengthens the concrete through a series of chemical reactions over centuries.

Its Most Famous Gelateria Is Over a Century Old

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By most accounts, Giolitti (the oldest gelateria in the city) — located just a couple blocks north of the Pantheon — is widely known due to its appearance in the classic Hepburn film Roman Holiday. Giuseppe and Bernadina Giolitti first opened a creamery on the Salita del Grillo in 1890. Soon, they were supplying dairy products to the Italian royal family. In 1900, they established the iconic location for which they are known today.

The gelateria is open from 7:00 a.m. to 1:30 a.m., every day of the year, meaning you can get a sweet treat almost anytime you want one.

The Largest Church in the World Is (Sort Of) Located Here

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St. Peter's Basilica, in the heart of Vatican City, is the largest church in the world. While technically not on Italian soil, the church is a common stop for visitors on religious holidays, when the pope addresses the crowds from the balcony overlooking St. Peter's Square.

If you don't venture into the Vatican, you'll still find many places of worship within the city. The commonly accepted wisdom is that there are more than 900 churches in Rome today, most of them Roman Catholic.

It Has Been Known as 'Hollywood on the Tiber'

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Cinecittà Studios, on the outskirts of Rome, was founded by Mussolini in 1937 and is still the largest movie studio in Italy. Throughout the 1950s and 1960s, it was the site of major Italian and American films.

Though the site's heyday is over, the studio grounds are still open to visitors today, where you'll see sets and props highlighting the storied history of Italian cinema.