It’s not difficult to stumble upon a Roman ruin while visiting Europe. Rome left its legacy all over the continent, and you can easily walk where toga-clad nobles walked, and disciplined legionnaires marched. Some of these ruins are small, while others are absolutely massive, and then there are those that impacted history so much that it still echoes today. When you’re in Europe, you should take an afternoon and visit one of these historic ruins.

No civilization has impacted the modern western world more than the Roman one. At the height of its power, Rome was the largest empire in the world, with over 60 million citizens from 100 different languages. The Empire’s borders stretched from the north of England to the deserts of North Africa, and from the wet Atlantic Ocean to the sub-tropical shores of the Black Sea.

The Roman Legions were the most feared military force of the time, and Roman civilization was spread mainly at the tip of the sword, but once a population had been subjugated the Romans began building exquisite roads, villas, aqueducts, and baths. Rome built the ancient world's most connected network of roads and ports, and their libraries, colosseums, and fortresses are famous.

Many of those sights are still with us today. These ruins are awe-inspiring for how well they were built, and the impact they had on Europe cannot be understated. From Hadrian’s Wall in northern England to the Colosseum in Rome, or the great aqueducts found in France and Turkey, here are 20 Roman ruins every visitor to Europe should see!

20 20. Isca (Wales)

Near the Welsh town of Caerleon, just outside the sprawl that is Newport, rests a massive Roman fortress built to house a Legion that could control and subjugate the conquered Welsh people of the area. The fortress was built around A.D 75 during the conquest of Britannia, and at the height of its power, it housed a garrison of more than 5,000 heavy Roman infantry along with cavalry and support personnel.

Today the roads of Caerleon follow the original roads laid down by the conquering Legions, and heading down Main Street will take you to a 3.5 meter (11 feet) high wall, part of the original fortress, as well turrets and a Roman bakery!

19 19. Chedworth Villa, England

The largest Roman villa in Britain is located in Chedworth, just outside Gloucestershire. The villa was part of a network of villas in the Cotswolds’ built in the second Century, once this part of Britain had been conquered and was Romanized. The villa itself disappeared from history during England’s turbulent history, until a gamekeeper tripped over a piece of mosaic sticking out of the ground in 1864.

Today you can wander through what would have been rooms and baths, and you can even see the kitchens and the grand, elegant courtyard where Roman nobility would have entertained each other!

18 18. Canterbury, England

Cantiacorum was considered the civic center of modern Kent during the Roman era, and the city of Canterbury is the same city which has continued to grow and thrive since those days. It is estimated that Celtic tribes lived here prior to Julius Caesar’s invasions in 55 BC, and it was quickly taken by the Legions and made into a Roman outpost in a hostile land. Traders and nobles and adventure-seekers followed the Legions, and the city continued to grow.

Today you can see evidence of the Romans all over the city. The Quenin Gate protects the inner-city, while Rome’s famous public baths can be found in the basement of Waterstone’s Bookstore!

17 17. Hadrian’s Wall, England

The second-most famous wall in Europe (after the Berlin Wall) was built in the year 122 AD to keep the wild Picts and Scots out of civilized Roman Britannia. The wall is 80 miles (117 km) long and traverses the northern tip of England. At the height of Roman power, the wall was 20 feet (6 meters) high. At one point it marked the very edge of the Roman Empire, where the rule of the Caesars stopped.

Today all that remains of the wall is the base, but you can stroll along it and enjoy the calm English countryside!

16 16. Pont Du Gard, France

Roman engineers built this astonishing 3-level aqueduct in southern France, just north of Marseilles, in the First Century to supply water to the nearby city of Nimes. This bridge was part of a 50-mile long aqueduct that could carry 20,000 tons of fresh drinking water from the rivers of the region into the towns and cities of Roman Gaul.

Today even architects marvel at the Pont Du Gard. Despite being 2,000 years old, it is still in fantastic condition and is as stable as the day it was built. Take a tour of the base of the aqueduct and see for yourself!

15 15. Roman Theatre of Orange, France

One of the best-preserved Roman ruins in the world is the Roman Theatre of Orange, in Vaucluse, France. The theatre is so well preserved that it is still used for drama festivals today!

The theatre was founded and built by soldiers of the Second Legion in 40 BC during Julius Caesar’s conquest of Gaul and used for several hundred years until it was closed by official edict in the fourth century. During the medieval ages, it was used as a defensive fortress by French knights, and again in the 16th Century by citizens fleeing the religious wars of the time.

Today you can go and watch pantomime and French theatre during summer festivals.

14 14. Emerita Augusta, Spain

In the middle of Nowhere, Spain, lies an ancient Roman city that was meant to be a place where retired soldiers could live out their golden years. Emerita Augusta is in the middle of Spanish desert, hundreds of miles from Madrid or Barcelona or anywhere. It is dry, and there are few roads or conveniences, but for the hardy traveler and history buff, there are Roman ruins galore!

As you approach Emerita Augusta, the world’s longest-standing Roman bridge greets you. Next to that is an amphitheater from the 1st Century. From there you can see the arches of the Temple of Diana.

13 13. Cartagena, Spain

If trekking into the Spanish hinterland doesn’t appeal to you, then saunter over to Cartagena, a Roman town which still thrives today as one of Spain’s tourist destinations. Luxuriate in a thermal bath, exactly where Romans relaxed two thousand years ago, and be sure to check out the Roman Forum and the Atrium. The Cartagena Roman Museum is overflowing with items salvaged from the ground, so be sure to spend an afternoon in its air-conditioned halls.

Cartagena was called “Cartago Nova” in honor of the city of Carthage, which the Romans burned to the ground two centuries before. Today Cartagena is a bustling city filled with Roman ruins!

12 12. Imperial Baths of Trier, Germany

Trier, in western Germany, is home to the largest Roman baths found outside of Rome. The city itself was one of the flourishing centers of trade and was often referred to as “The Second Rome.” Emperor Constantine the Great began massively developing the city in the fourth century, and today it is one of the most impressive Roman sites found anywhere in Europe!

The baths themselves are all dried up now, but the buildings and rooms are all there. When you enter, you are greeted with a bathing area which today hosts opera performances and seats over 600 people!

11 11. Ostia Antica, Italy

Near the city of Ostia on Italy’s west coast, just a short drive from Rome, are the amazing ruins of Ostia Antica. The town was called simply Ostia in Roman times and served as the main port for grains, slaves, wines and other luxuries flowing into Rome from all over the Empire.

Today you can walk the streets and see the now-dried-up harbor. Visit the public baths, the public forum where exotic goods from all over the Roman world were for sale. For $50 US, you can have a have a tour guide help you explore this wonderful Roman town.

10 10. The Appian Way, Italy

The Appian Way is the road that leads from Rome to the strategic port city of Brundisium on the heel of the Italian boot, 350 miles away. Built in 312 BC, this 2,500-year-old road can still be walked along today! Many tombs of Senators, Emperors and rich Roman citizens are dotted along the Appian Way leading to Rome, and you could spend an entire day walking along the statuary and ancient Roman plaques.

Start your tour at the Gate of San Sebastio, or buy a tour with a knowledgeable guide, and enjoy your stroll through history!

9 9. Pompeii, Italy

Be sure to visit the famous Roman ruins of Pompeii, which were perfectly preserved under a mile of ash for two thousand years when Mount Vesuvius erupted and buried the busy Roman city. The city, including its inhabitants, was perfectly preserved under the ash where there was no air or moisture. The shops, homes, stables, baths, and streets of the city can be seen just as Romans saw them. Sadly, the bodies of the victims of the volcano were encased in ash, leaving behind haunting casts of people in their last moments of life.

Macabre aside, the city is open to tourists, as is a trek up the volcano!

8 8. Arch of Constantine, Rome

You can’t avoid the Arch of Constantine while you’re in Rome. Towering next to a main artery through the center of the town, next to the ruins of the Colosseum, this massive arch was erected by Emperor Constantine in 315 AD and is one of the better-preserved monuments in the city.

Constantine erected the arch after winning a bloody civil war and crowning himself Caesar, so the Senate built the arch to thank him (and to curry favor). It’s easy to reach the arch. There are several subway stops right next to it, and if you’re out touring the Roman Forum, you can’t miss it.

7 7. The Colosseum, Rome

What’s a list of Roman ruins without the famous Colosseum? This massive wonder of the ancient world is one of the most visited sites in Europe. According to answers.com, 5 million people trek through the ancient building each year, so why not be one of them?

Back in the year 72 AD, Emperor Vespasian commissioned the largest amphitheater ever built anywhere in the world, and during the bloody and epic gladiator games that took place here, more than 80,000 spectators would cheer on their heroes.

You can book a guided tour, which will give you access to the basement levels where slaves, gladiators, prisoners and exotic animals were held.

6 6. The Forum Romanum, Rome

When in Rome, you must visit what was the political and economic center of this powerful Empire. During the Republic period, before Julius Caesar started the Empire, the Roman Forum was where speeches were made, Senators vied for election and where crowds gathered to hear the news. The Forum Romanum continued to be a sprawling marketplace and center of intrigue and gossip during the Imperial era.

Today you can stroll along its avenues and view the arches and statues that once towered over everyone. Visit the Temple of Saturn and be sure to take in all the triumphal arches erected by Emperors with big egos.

5 5. Butrint, Albania

Rome’s empire stretched far to the east, and in today’s Albania, you’ll find Butrint, formerly known as Butrinti. These ruins are situated in a calm, peaceful Albanian forest, where you can find an amphitheater, public baths, a temple and several well-built roads leading to Roman houses.

The town was established by Julius Caesar in the first century, although Greeks had settled in the area four hundred years earlier. You can also visit several medieval castles overlooking the nearby lake, or simply enjoy a nice hike through the gentle forest which has grown over the ruins!

4 4. Pula, Croatia

Often called “The Other Colosseum”, the Pula Arena is the second largest Roman amphitheater in Europe after the big one in Rome. Unlike the one in Rome, the Pula Arena is in such great condition that you can tour around it and even visit the museum in the subterranean vaults below it!

Next, you’ll want to visit the Cathedral of the Assumption, which used to be a Roman temple until the fifth century. Nearby is the inevitable forum, where people bartered for goods, gossiped and listened to news and proclamations from the capital.

3 3. Philippi, Greece

Greece has plenty of its own ruins, and Rome added some of its own after the conquest of this ancient land in 146 BC. Philippi is one of the most spectacular sites in Greece thanks to the ruins from three civilizations piled on top of each other: Macedonian, Greek, and Roman.

Enjoy strolling along the Roman forum and then pondering the vast columns of a Greek temple, while a bust of Alexander the Great lays toppled over nearby. This UNESCO World Heritage Site is strictly controlled, so be sure to follow directions while visiting.

2 2. Olympos, Turkey

Turkey is filled with ruins from multiple civilizations, and for a long time, Asia Minor was the home of the Imperial Roman capital at Constantinople (today’s Istanbul). Leave the bustle of this massive city and head to the south shores of Turkey where you’ll find Olympos, one of the most peaceful and least-visited Roman ruins on this list.

Olympus was a Greek city which was conquered by the Romans, and then became a flourishing Roman port famous for spices and jewels from as far away as India and even China. Today you can see walled gardens, villas, wide boulevards and the ever-present Roman baths.

1 1. Valens Aqueduct, Turkey

Istanbul was formerly Constantinople until the Turkic nomads swept down out of the mountains and conquered the city in 1453. Until that date, it was the capital of the Eastern Roman Empire, and nothing in Istanbul reminds you of that more than the Valens Aqueduct.

This massive two-story aqueduct was built by Emperor Valens in the fourth century and was used as a functioning aqueduct right up until the fall of the Ottoman Empire in 1918! It cuts across a major road, and you are free to stroll along it, marveling at the awesome engineering of that once-awesome empire!