Bulgaria has the greatest number of archaeological sites in Europe after Greece and Italy. Every tour guide worth their badge has proclaimed this at least once to Bulgarian and foreign tourists. The adage is a compelling image of the country, but it is misleading. The great majority of Bulgaria's archaeological sites are interesting to archaeologists only and/or are in a condition that is hardly inspirational or Instagram-friendly: overgrown, looted by treasure hunters, devoid of tourist infrastructure and even signage.

As a country located at the crossroads between Asia and Europe, what is now Bulgaria was settled soon after Homo sapiens emerged from Africa. Palaeolithic hunter gatherers lived in its caves and the first farmers arriving from the Middle East settled on its fertile plains en masse. Generations later, their descendants crafted the first documented gold objects in the world near modern Varna.

The most spectacular archaeological sites in Bulgaria today were created by four distinct cultures and civilisations that came after. The ancient Thracians left behind spectacular rock shrines and sites, dolmens and tumuli hiding impressive tombs. The Romans built their trademark planned cities complete with theatres, public baths, forums and basilicas. The Medieval Byzantines and Bulgarians created hilltop fortresses and beautiful churches with intricate architecture and distinctive murals.

On the following pages you will see some of the most impressive places that all of these peoples left behind.

Magura Cave

When: 50,000 years ago, or the Neolithic, or the 1st millennium BC

Why: Bulgaria's only prehistoric rock art

Dancing women, strange creatures and even stranger suns, moons and other celestial bodies: the guano drawings at the Magura Cave, in Bulgaria's northwest, might be crude but are mesmerising.

Magura is one of Bulgaria's largest caves – it is 2,608 metres long and 56 metres deep. It started forming about 15 million years ago and is now packed with stalagmites, stalactites and stone columns, a small lake, plus a colony of eight bat species.

What makes the Magura outstanding is its gallery of prehistoric drawings. These figures of people, animals, birds and geometrical shapes are still puzzling. Some of the scenes have been interpreted as hunts, others as religious rituals, and possibly as a form of early calendar. How early is hard to say: the Internet attributes some of the drawings to Neolithic and even Palaeolithic people but, according to historians, they can be dated much later, from the 1st millennium BC.

Bishop's Basilica of Philippopolis

When: 1st-14th centuries

Why: An outstanding example of sensitively preserved archaeological heritage

With its ancient theatre and stadium, fortification walls and streets, an aqueduct and a museum full of statues, tombstones, mosaics and inscriptions, Plovdiv is the place in Bulgaria to visit if you are interested in Roman heritage. Even in this highly competitive environment, the Bishop's Basilica of Philippopolis stands out.

A decade ago only a couple of people were aware that in central Plovdiv lay the ruins of a large early-Christian basilica with exquisite mosaic floors depicting scores of birds. Today, the Bishop's Basilica is Bulgaria's latest and most modern museum, thanks to the efforts of the America for Bulgaria Foundation and the Plovdiv City Council.

By using traditional storytelling and modern technology, the exhibition reveals how the site transformed over the 14 centuries of its history. What started as a pagan temple became a lavish early-Christian basilica. When it was abandoned, its grounds became the site of a large medieval necropolis.

Cherven Fort

When: 11th-18th centuries

Why: Authentic fortifications in stunning landscape

In Bulgaria, it is easier to visit an ancient or a medieval fortress that was completely rebuilt in the 1980s or the 2010s, rather than a site that has barely changed since the Middle Ages. Cherven, near Ruse, is the most spectacular of these rare exceptions.

Perched at a picturesque bend of the Cherni Lom river, Cherven Fort started as a Byzantine fortification that later grew into a major city. It had splendid churches, prosperous traders and craftsmen – and strong walls to protect them. A number of rock churches appeared at nearby Ivanovo, now an UNESCO World Heritage Site.

The fortress suffered heavily during the Ottoman invasion, and was destroyed in 1388. However, Cherven remained the main city in the area until the 18th century, when people gradually resettled on the banks of the Danube, in today's Ruse.

Cherven's most impressive structure is its three-storey defence tower. In the 1930s, it was used as a model for the reconstruction of the so-called Baldwin Tower, in Veliko Tarnovo's Tsarevets Fortress.

Sveshtari Tomb

When: 3rd century BC

Why: You visit the real thing, not a replica

Bulgaria has three impressive art-decorated Thracian tombs: the Kazanlak, the Aleksandrovo and the Sveshtari. The first two are closed for the general public and visitors have to go to replicas instead.

The Sveshtari Tomb is the real thing, and is unique in the Thracian world because its burial chamber is decorated with both frescoes and sculptures. The wall painting depicts an imposing woman crowning a rider with a wreath. Ten limestone caryatids line the walls. Their oddly proportioned bodies, intricately carved dresses and broad faces with wide-open eyes capture your imagination in the claustrophobically narrow chamber. Both the Sveshtari caryatids and the tall woman in the fresco are believed to represent the all-mighty Great Goddess of the Thracians. The rider in the mural was probably a deified Thracian king, receiving his immortality from the Great Goddess. He was also supposedly buried in that very same tomb.

In 1985, UNESCO listed the Sveshtari Tomb as a World Heritage Monument. The tomb was recently renovated with US government funding.

Ulpia Oescus

When: 1st-6th centuries

Why: Feel like a discoverer

Finding yourself among the splendid ruins of an ancient city, with few traces of tourist infrastructure or other people around, is an experience that might have been common in the 19th century. Ulpia Oescus makes it possible in the 21st. Just outside the nondescript village of Gigen, a stone's throw from the Danube, the streets and temples of a Roman city spread out, overgrown with thick shrubs, and only partially excavated by archaeologists.

The city started out as a major military camp established by the Romans to control this part of their Danubian border. It quickly grew and gained prominence – in 106 Emperor Trajan promoted it to the status of a proper city. In 328 Emperor Constantine visited Oescus for a special event – the inauguration of a bridge over the Danube.

The city withstood a number of Barbarian attacks, until the Avars brought about its complete destruction.

Today, the ruins of Oescus are not signposted, and the site is in a picturesque state of dilapidation, with marble friezes and columns lying among the undergrowth – a real delight if you grow tired of modern reconstructions of ancient sites.

Perperikon

When: From the Neolithic to the 14th century AD

Why: This is the "Bulgarian Machu Picchu"

The rock city of Perperikon, near Kardzhali in the Rhodope, is one of Bulgaria best known and most visited archaeological sites, and rightfully so. From Neolithic times until the Middle Ages, the hill was inhabited by people who continually carved into the bedrock sacrificial altars, cisterns, graves, wall foundations and churches.

The theory that Perperikon was the oracle of Dionysus, famous in Antiquity for predicting the glorious future of Alexander the Great and the Emperor Augustus, has also played a role in the popularity of the site. The city is worth visiting more than once for many reasons. It affords magnificent views of the surrounding countryside and the ongoing excavations change the appearance of the rock city every season.

Deaf Rocks

When: 12th century BC – 14th century AD

Why: Mysterious rock niches

For centuries, people lived, worked and prayed on a rocky peak in the Eastern Rhodope, changing their religion from time to time, but not their culture. No, this is not Perperikon, but another, lesser known ancient city, at a location now known as Gluhite Kamani, or Deaf Rocks. 

The most spectacular part of the site are the niches cut in every vertical rock surface around. They were carved, often at precipitous heights, by the ancient Thracians in the 1st millennium BC. No one is sure how or why they did this. The niches might have contained urns with the remains of the cremated dead, or might have been carved as a part of an initiation ritual, or could be symbolic representations of the womb of the Great Goddess. Equally, they might be something entirely different.

Archaeologists have excavated Gluhite Kamani for years, but the mystery of the niches (they are not unique to this site) persists.

Hlyabovo Dolmen

When: 9th-8th centuries BC

Why: Peek inside Bulgaria's largest preserved dolmen

Centuries before the ancient Thracians started burying their noble dead in impressive tombs, they used megaliths – dolmens, or house-like structures built of heavy rock slabs. The result of this practice was thousands of dolmens in Bulgaria's southeast. Now, most of these are gone, destroyed by treasure hunters and farmers who saw them as obstacles to large-scale agriculture.

The dolmen at the Hlyabovo village is a reminder of what has been lost.

When it was discovered, it was hidden under a 10-metre mound. It has a layout and structure unmatched so far: two attached dolmens with two chambers each, and a monumental façade. The stones covering them are still in situ. The intact human remains found in one of the chambers were a breakthrough, the first time for a dolmen in Bulgaria.

Silistra Tomb

When: 4th or 5th century AD

Why: Glimpse into what living in style before a Barbaric invasion was like

Bulgaria's best known tombs were created by the Thracians, but in Silistra you will find an exception. This beautifully painted sepulchre was created by a refined Roman who had the misfortune to live in turbulent times at the borders of a declining empire under frequent Barbarian attack.

The tomb's owner must have felt safe enough to order a nice final resting place for himself and his wife. He had a skilled master painter decorate the interior with an array of birds and flowers, symbolising the pleasantries of afterlife, along with portraits of the owner and his wife, and their servants carrying their finery and all the expensive objects that might come in handy in the afterlife.

The tomb was never used as intended: its owner probably died in a Barbarian attack or fled, never to return. The tomb is now surrounded by a purpose built building for protection.

Kaliakra Fortress

When: 1st-15th centuries

Why: Dramatic location on the Black Sea complement dark legends

A medieval fortress on a cliff over the choppy sea: the walls and gates of Kaliakra Fortress are mostly a 20th century reconstruction, but the site is on our list for its historical importance and beauty.

The Romans were the first to fortify the protruding, rocky Kaliakra Cape. The place grew in prominence in the 14th-15th centuries, when local nobles turned it into a stronghold and through clever political manoeuvring made it into a major player in the region. The best known of these was Prince Dobrotitsa, who successfully maintained a balance between the Bulgarian king in Tarnovo, the Byzantine emperor in Constantinople, the pushy Venetian and Genovese merchants, and the Ottomans who had just arrived and were eager to conquer. Kaliakra eventually fell to the Ottomans, and never recovered its status.

This disaster gave birth to two legends. One tells of 40 Bulgarian maidens who plaited their hair into a single braid and jumped into the sea to avoid capture. The other recalls St Nicholas running from the Ottomans and praying for salvation. With each step the holy man took towards the sea, God created new land under his feet. Eventually St Nicholas fell and the process of divine land formation stopped as the saint was killed. A chapel dedicated to him now stands at the supposed place of his death, on the very tip of the Kaliakra Cape.

Karanovo Tell

When: From the Neolithic to the Bronze Age

Why: See what the accumulation of millennia of human history at one place looks like

A huge, barren hill, carved up like a giant cake by archaeologists: Karanovo Tell, near Nova Zagora, does not look particularly fascinating. This impression lasts only until you realise that this 13 metre high and 250 metre long landmass was created by generation after generation after generation of continuous human habitation.

The people who first settled here were Neolithic farmers who recognised the potential of the area's fertile lands. They never left. For the next 3,000 years, while the climate, and human inventions and ideas changed and developed, people continued living in this place. When their houses burnt down, they simply built new ones over the remains. With time, the settlement rose to become an artificial hill, from which archaeologists call tell how the various waves of settlers lived.

Karanovo was not an isolated phenomenon, but just one in a vast network of prehistoric tells that grew up in what is now Bulgaria. However, Karanovo is the largest and longest inhabited of these.

Bacho Kiro Cave

When: 45,000 years ago

Why: See where the "first Europeans" lived

The history of early Homo sapiens and other human species is constantly being rewritten. One of the central questions that still awaits a definitive answer is how and when our ancestors replaced the Neanderthals, who used to dominate Europe. A couple of years ago Bulgaria provided a piece of the puzzle, when an amazing discovery was made in a cave in the Stara Planina.

Human remains discovered in Bacho Kiro Cave showed the first evidence of Homo sapiens in Europe at a time when the Neanderthals were still thriving on the continent. The find proves that the two species were coexisting together as early as 45,000 years ago.

The cave itself is also of some beauty and the nearby Dryanovski Monastery is a popular tourist site.