Everyone has heard about the Valley of the Egyptian Kings, but Bulgaria has its equivalent. The Valley of the Thracian Kings is a region where you can explore the tombs, mounds and treasures of what many historians consider to be the forefathers of modern Bulgarians.

The Thracians inhabited what is now Bulgaria roughly between the 2nd millennium BC and the 6th century AD. Over this long period of time they created a rich and diverse heritage that now comprises some of the most fascinating archaeological sites in Bulgaria: megalithic rock shrines, splendid tombs, and gold treasures.

Some of the most astonishing archaeological discoveries in the 2000s were made in the Giolyama Kosmatka mound

The Thracians lived all over Bulgaria, but the valley between the Stara Planina and the Sredna Gora mountain ranges is where the concentration of their sites is at its highest. The modern town of Kazanlak is roughly in its centre. The term the Valley of the Thracian Kings was coined by Dr Georgi Kitov, the archaeologist who worked in the area in the 1990s and 2000s and made some of the most fascinating discoveries there. The region, he argued, had been part of the mighty Odrysian Kingdom and the preferred burial ground for the Odrysian nobility for centuries, resulting in the creation of about 1,300 tumuli. Of them, about 300 have been archaeologically researched.

Among so many mounds and tombs, one stands out: the Kazanlashka Grobnitsa, or the Kazanlak Tomb. It was discovered long before Dr Kitov, and completely by chance.

The entrance of the copy of Kazanlak Tomb. Next to it is an abandoned Muslim shrine

On 19 April 1944 a group of Bulgarian soldiers were digging a trench in a massive 40-metre-wide mound, topped with the brick-and-mortar remains of a deserted türbe, or a shrine over the tomb of a Muslim saint, when their shovels struck a stone wall. The men broke through the wall and found themselves in a short corridor. A stone door lay broken on the ground, and frescoes of fighting men covered the walls.

The soldiers immediately called the director of the local history museum, Dimitar Chorbadzhiev, who, under the pen name Chudomir, happened to be one of Bulgaria's most beloved short-story writers. He recognised the importance of the discovery, and called for professional archaeologists.

The painted corridor led the archaeologists into a small chamber – 2.65 m wide and 3.25 m in height – with a beehive-shaped cupola covered with even more impressive frescoes, one of the best preserved examples of ancient European painting ever discovered.

The murals of the Kazanlak Tomb still hold this distinction. The fighting men in the corridor seem alive with their energetic movements, although it is not clear if they represent a battle won by the dead owner of the tomb, or are playing a commemorative game. In the burial chamber, three chariots chase each other, in an eternal circle, around the keystone of the cupola.

The exquisite murals of Kazanlak Tomb are the reason for its UNESCO World Heritage status

It is the main frieze in the burial chamber that makes the Kazanlak Tomb such an important place to see. Depicted there, a man and a woman feast, surrounded by musicians, servants and their beautiful purebred horses, but the mood of the scene is far from jovial. It is true that Herodotus wrote that some Thracian tribes celebrated the deaths of their loved ones, as they believed that dying liberated men from the sorrows of earthly life, taking them to a better place. However, the beautiful face of the veiled woman, who is sitting next to the wreathed man, her white hand gently resting in his, is unmistakably sad.

The meaning of the scene is open to interpretation. It could depict the funeral feast for a man who was deified after his death. Another version sees it as the mythological wedding of a god-like man and the daughter of the Great Goddess. The Great Goddess herself appears in the fresco: the tallest of all the figures in the frieze, carrying a plate with pomegranates, the fruit associated with the afterworld.

Whatever the meaning of the frescoes, their mastery is indisputable. The tomb was probably painted by a Greek painter in the first half of the 3rd century BC.

Inside the tomb at Golyama Kosmatka mound

In 1979 UNESCO added the Kazanlak Tomb to its World Heritage List. Due to preservation issues, the tomb is closed to the public, but visitors can tour an exact replica, a few steps from the original.

The Kazanlak Tomb aside, the greatest concentration of monumental mounds is between the modern town of Shipka and the village of Kran, a few miles north of Kazanlak.

Built in the 4th century BC, the Ostrusha Tomb near Shipka preserves another small but emotive example of fresco painting – on the ceiling is the face of a fine lady with white skin and red hair. The architecture of the tomb is also remarkable. It was hewn into a monolithic stone block which was covered with another monolith, carved in the shape of a Greek temple roof. The structure was surrounded by several other buildings, of which, sadly, only the foundations have been preserved.

The Kazanlak and Ostrusha tombs, along with many more in the area, had been plundered by ancient or modern treasure-hunters, but in 2004 the team of Dr Kitov working in the Valley of the Thracian Kings literally struck gold – twice.

The golden mask, discovered in the Svetitsata mound, supposedly belonged to the Thracian King Teres

In August the team were excavating an ostensibly uninteresting stone grave in the Svetitsata Mound, near Shipka, which had belonged to a Thracian aristocrat from the second half of the 5th century. Despite its unpromising appearance, the contents of the grave within were amazing: a collection of top-quality weapons and expensive imported vessels, and a 673-gram gold mask of a bearded man. The skeleton of the deceased was there, though some of the bones were missing, suggesting posthumous ritual dismembering.

Why did the Thracians do that? They were probably recreating the myth of Orpheus, who was torn apart by the Maenads, or of Dionysus, who was destroyed by the Titans. The dismemberment might point to the deceased being a follower of the mystic teachings of Thracian Orphism.

For Dr Kitov the man in the mound had to be none other than the Thracian king Teres (turn of the 6th century BC – 450/448 BC), and although some historians remain unconvinced, the find and the mound are publicly promoted as connected to Thracian royalty.

A replica of the bronze portrait discovered at Golyama Kosmatka mound

The media were still in a frenzy over the Svetitsata finds when, in September, Dr Kitov's team made the news again. In the nearby Golyama Kosmatka mound they discovered one of the biggest and best preserved aristocratic tombs in Bulgaria.

The tomb has a 13-metre-long corridor and two antechambers, the second of which is round, has a 4.5-metre-high cupola and is protected by a marble door with medallions of the faces of Helios and Medusa. Behind is a rectangular burial chamber hewn into a 60-tonne monolith, which contained more than 70 items: a wealth of expensive weapons and precious objects, including a beautiful gold wreath.

The words "To Seuthes," inscribed on one of the silver vessels and on a bronze helmet found there, have led some historians to conjecture that the tomb belonged to King Seuthes III (ca. 330-300/295 BC). Others, however, dispute the identification, as Seuthes had died decades before this burial took place – some time around 280 BC.

A gold wreath

The most astonishing find from Golyama Kosmatka was discovered buried in the mound, not in the tomb itself. It was a beautiful bronze head of a man with an unruly beard and strong features. The head was probably an effigy of the deceased, and was cut from an actual, life-sized statue: another dismemberment, this time symbolical.

Built probably at the end of the 4th century BC, the Shushmanets tomb is another intriguing example of Thracian burial architecture in the region. The entrance is decorated with a column in the Ionic style, an obvious influence from Greece. In the round chamber, there is another column, a Doric one.

It would be understandable if, after reading about so many tombs, you started to think that the Thracians were so preoccupied with death that they didn't care about the living. The Valley of the Thracian Kings indicates this was not necessarily so. The evidence is the city of Seuthopolis.

The city was built after 315 BC, on the whim of King Seuthes III. At the time, he was at the height of his power and had enough money and ambition to follow the fashion set by the Macedonian kings Philip II and Alexander the Great – to found a capital city and bestow on it his name. The new city resembled any other in the Hellenistic world. Its paved streets ran straight, and there was an agora, or open-air area for the citizens to meet, talk and do business. A portion of the city was reserved for the king and his family.

The still waters of Koprinka Dam hide the remains of the Thracian city of Seuthopolis

Seuthopolis did not survive long, and was abandoned by the middle of the 3rd century BC. A village appeared on the site in the Middle Ages, but it too did not last, and soon earth covered the remains of the forgotten Thracian capital.

The city of Seuthes was discovered in 1948 in unfortunate circumstances, as the area was being surveyed before it was submerged under the planned Georgi Dimitrov reservoir. The scientific importance of the discovery was incredible, but the Communist government wanted to industrialise the country as quickly as possible, and water supply was seen as more important than preservation of history. Archaeologists were given six years for excavations – the time it took to construct the dam – and they did all they could before the waters finally closed over, drowning the only design-built Thracian city preserved in Bulgaria.

Seuthopolis remains at the bottom of the reservoir (now called Koprinka) and some of its finds are on display at the Iskra Museum of History at Kazanlak. There was a bold plan to reconstruct the city and turn it into a tourist attraction but it never materialised. Now visitors can only walk on the dam wall, look west, and imagine the subaqueous archaeological treasure.

The so-called Goddess Gate megalith near Buzovgrad is said to be created by the Thracians as a shrine and an astronomical observatory. In reality, it is a natural phenomenon 

The area is also known as the Valley of Roses, one of the few places where oil bearing rose thrives

The golden-domed Russian church at Shipka is another sight of interest in the region. It was built to commemorate the fallen soldiers in the 1877-1878 Russo-Turkish War