(CNN) — Ancient sites open your mind to just how old "old" can be and how sophisticated our ancient ancestors were in devising their artistic, engineering and construction methods. You'll never equate "ancient" with "primitive" again.
You don't need us to call your attention to the Colisseum in Rome or the pyramids in Egypt. So, like archaeologists, we're digging deep for a list of lesser-known ancient ruins.
Our definition of "ruins" includes some sites that are mere shadows of their glory days and others that have been protected or preserved since, virtually, the beginning of civilization.
We recognize that some of these destinations are not recommended for tourists at the present time. But current geopolitical issues do not diminish their historical importance, and we'd be remiss if we overlooked them.
1. Haskovo, Bulgaria
The words "ancient history" probably don't bring Bulgaria to mind, but perhaps they should. It's loaded with archaeological sites, especially from the Thracians, whose society entered its most influential period around 1000 BC. By some estimates, Thracian burial mounds in Bulgaria number in the tens of thousands, and many contain artifacts and treasures. Right now, the most famous of these is the Alexandrovo Tomb in the municipality of Haskovo.
The 4th century BC tomb was opened by archaeologists in 2000 to reveal colorful wall murals depicting battle scenes, hunts and other activities. Making the site accessible to visitors was impractical, so instead, a full-scale replica was recreated for a museum that also houses golden ornaments and other treasures recovered from the site.
2. Diocletian's Palace, Split, Croatia
A career military man from an ordinary family, Diocletian was born in nearby Salona (now Solin) around 244 AD and rose to become emperor of Rome around 285 AD.
He ruled for 20 years. Then, around 60 with his health failing, he abdicated and retired to Split near the Adriatic Sea, grew vegetables and relaxed until his death in 311 AD.
The Roman palace was the greatest of its time, and the Peristyle courtyard where the emperor greeted the citizenry is now the site of a daily changing of the guard ceremony featuring mock Roman soldiers. Later medieval portions of the palace include St. Duje Cathedral, built over the Mausoleum of Diocletian -- ironic since Diocletian was known for his persecution of Christians.
3. Kourion and Paphos, Cyprus
Like many archaeological sites in Cyprus, Kourion adapts its ancient heart to modern usage. Its 3,500-seat amphitheater, which has existed in some form since the 2nd century AD, is still a venue for musical and theatrical performances.
Though an earthquake in 364 AD leveled the city, its mosaics survived. They're outstanding, particularly the 3rd century AD scene of gladiators Margarites and Hellenikos locked in mortal combat.
Its proximity to the cruise port of Limassol makes Kourion a popular shore excursion. Farther up the coast, the archaeological sites at Paphos include another collection of excellent Roman mosaics and Hellenistic ruins.
4. Thebes, Egypt
At this ancient site near modern-day Luxor, Middle Kingdom (around 2050 to 1640 BC) and New Kingdom (1550 to 1070 BC) pharaohs built temples to their gods, tributes to themselves while they were alive and tombs to proclaim their glory after they'd died. The temple complex at Karnak, monumental in size and scope, developed over generations as rulers added to, remodeled or demolished what had been built before. (Thutmose III waged quite a campaign to obliterate the name and image of his stepmother/aunt Hatshepsut.)
Evening visits include a sound and light show. A long promenade flanked by sphinxes connects the temple complex at Karnak to the equally awe-inspiring temple at Luxor. Across the Nile are the royal tombs -- including the tomb of Tutankhamen -- in the Valley of the Kings.
5. Roman sites in Arles and Nimes, France
In the 1st century BC, when Arles was called Arelate, its residents wisely sided with Julius Caesar in a battle against Pompey. When he prevailed, Caesar rewarded them by making Arles into the "Little Rome of the Gauls." In its time, the city's Roman amphitheater sat 20,000 spectators.
Today, it's a venue for mock gladiator contests in summertime. Les Thermes de Constantin, built in the 4th century AD, are Roman baths warmed by a remarkable hot air flow system.
Nimes, less than 20 miles away, also benefited from Caesar's victory. Its Roman sites include a beautifully preserved amphitheater. About 30 minutes from Nimes is the Pont du Gard aqueduct, a masterpiece of precision engineering that fed the city with 2 million liters of fresh water every day. Its construction is so ambitious it's hard to believe it dates back to the 1st century AD.
6. Mycenae, Greece
In Mycenae, German archaeologist Heinrich Schliemann unearthed the golden "Mask of Agamemnon" from a tomb in 1876. Or, at least, he claims he did. Schliemann was an enthusiastic digger but an unreliable chronicler of his finds. While the mask may or may not have come from Mycenae, it almost certainly had nothing to do with Agamemnon, the mythological 14th-century BC king.
The Mycenaean empire, however, was real and extremely influential in the ancient world. The site is in ruins, but the Lion Gate of the former palace from around 1300 BC still stands and the remains of the beehive-shaped tholos tombs reserved for royalty are still being studied and excavated.
7. Masada, Israel
Herod the Great, King of Judea, could not have chosen a more dramatic site for his palace and stronghold, atop a cliff on the edge of the Judean Desert. But when he built it in the 1st century BC -- in part as protection from possible invasion by the Egyptians -- he couldn't have known Masada would become the Jewish people's last line of defense against the Romans, who stormed it in 73 AD.
Scholars still debate the "official" account of events by 1st-century historian Josephus, but Masada's ingenious engineering is indisputable, from the grand palace to the 2,000-plus-year-old system to capture rainwater for drinking, bathing and irrigation. Climb to the top like a Roman via the "snake path" or take a cable car from the visitor's center.
8. Tarquinia and Cerveteri, Italy
Before there were Romans, there were Etruscans, a distinct civilization with its own language, practices and social structure that thrived in Italy from 750 to 90 BC.
They're not as well-studied as the Romans (few civilizations are), but they're known for their elaborate burial practices and the huge necropolises they left behind.
The sites at Tarquinia and Cerveteri (formerly Caere) -- both in Italy's Lazio region on the Tyrrhenian Coast -- are true "cities of the dead" with streets, houses and neighborhoods. The subterranean tombs contain stunning murals of everyday scenes that help historians understand how the Etruscans lived as well as how they were treated when they died.
9. Jerash, Jordan
Jerash (Gerasa to the Romans) isn't as well-known as Petra, but it's older, superbly preserved and just 30 miles from Amman. It's also the venue for the annual Jerash Festival, two weeks of music, dance and other performances amid the ancient Roman ruins.
It's possible Alexander the Great founded Jerash, but the Romans who conquered it in 63 BC put it on the map. By the 2nd century AD, it was a prosperous city. A few hundred years later, it was in decline, and by the 19th century, it was buried in sand. There it remained untouched and perfectly preserved until archaeologists began digging it out in the 1920s in a process that continues today.
10. Dolmen sites, Korean Peninsula
A dolmen doesn't look like much: a large rock balanced on slightly smaller, yet still quite large, rocks. Then you stop and ponder how in the world it was constructed. There were no motorized cranes to do heavy lifting in 1000 BC, and those rocks weighed tons.
Dolmens, which were enormous grave markers and portals to the afterlife, are found all over the world, which in itself is something to ponder since they were built by civilizations that seem to have little else in common.
The largest concentration is in the Korea Peninsula. Sites at Gochang, Hwasun and Ganghwa in South Korea are inscribed on the UNESCO World Heritage list. Start with a primer at the Gochang Dolmen Museum before touring the sites.
11. Mnajdra and Hagar Qim, Malta
When they were placed on the UNESCO World Heritage List, the "megalithic temples" of Malta were called "the oldest free-standing monuments in the world." There are seven on the UNESCO list. Mnajdra and Hagar Qim near the town of Qrendi on the island's south coast are arguably the best of the group -- plus, they're included on a combined price of admission.
The oldest structure at Mnajdra could date back to 3600 BC, the most impressive was built before 2500 BC and the orientations of all the Mnajdra temples coincide with the position of the sun at the summer and winter solstice. Hagar Qim was built around the same time.
12. Lumbini, Nepal
In 623 BC, Queen Maya rested in the serene gardens of Lumbini. She bathed in the Pushkarini Pond, and there, in the shade of a sal tree, Prince Siddhartha Gautama -- the Buddha -- was born.
In 249 BC, Emperor Ashoka erected a pillar at Lumbini to mark the precise place of the Buddha's birth. He also declared that residents of Lumbini no longer were required to pay taxes and only owed the government one-eighth of their harvests.
Since then, Lumbini has been a pilgrimage site for Buddhists. Remains of monasteries and walkways from the 3rd century BC are still there, and recent archaeological excavations have unearthed evidence that the site was in use much earlier. Active monasteries and temples fill the surrounding area.
13. Carthage, Tunisia
In the third century BC, when the Romans conquered just about everything they cared to, Hannibal, the military commander and strategist from Carthage who famously crossed the Alps on an elephant, made them quake in their sandals.
Even though they sacked it in 146 BC, the Romans rebuilt Carthage, and it remained a trading port on the Gulf of Tunis for centuries. Highlights of the site include the Roman era Antonine Baths and the Punic era Tophet burial site once thought to be the scene of ritual child sacrifice -- a theory that, thankfully, has been debunked.
14. Hattusha, Turkey
Hattusha was the capital of the Hittite Empire, whose relics include an archive of more than 25,000 cuneiform tablets. Most famous of these is the Treaty of Kadesh, guaranteeing "eternal peace" between the Hittites and the Egyptians.
There's evidence that Hattusha was attacked and burned in 1700 BC --indicating that it was established and important enough to be a target that early, although the empire was at its strongest from around 1600 to 1200 BC.
Today, Hattusha is an open-air archaeological museum, and the ancient sanctuary at nearby Yazılıkaya has extraordinary religious rock carvings. In 2011, the nearby Boğazköy Museum added to its collection two Hittite Sphinxes, one of which had been taken to Germany "for repairs" 94 years earlier.