What happens after death has fascinated people since the dawn of humanity. The earliest accounts of what they thought was the answer paint a glum picture. According to the ancient Mesopotamians, the dead inhabited a grim realm where they had only dust to eat and drink. Ancient Egyptians striving for an afterlife had to be mummified and to undergo a strict vetting process, under threat of being eaten by a monster in case they failed. The ancient Greeks were aware that even the greatest heroes would be reduced to nameless shadows in the Kingdom of Hades.

The ancient Thracians, the people who inhabited what is now Bulgaria between the 2nd millennium BC and the 6th century AD, had other ideas. They celebrated death. According to Herodotus, the Thracians believed that death freed one from all the pain and sorrow of life. They mourned newborns. When a man of prominence died, Herodotus writes, the Thracians would organise festivities and sporting events, while the deceased's wives would quarrel about which of them was his favourite and deserved to be buried with him.

Herodotus often got his stories wrong, but a number of archaeological discoveries seem to support his report on the Thracian way of dying.

The Kazanlak Tomb, a UNESCO World Heritage Site, is arguably the most impressive. Its murals are both a rare example of ancient art and compelling evidence about the beliefs of the ancient Thracians.

Beautiful horses are among the most precious possessions of the tomb's dead owner. He wanted to take them into the afterlife – both figuratively and literally. In the tomb's corridor horse bones were found – remains of the Thracians’ well documented practice of horse sacrifices

It was discovered purely by chance.

On 19 April 1944 a group of Bulgarian soldiers were digging a trench in a 40-metre-wide mound. The mound did not look artificial at all, and gently blended with a natural hill. Centuries before, a shrine to a Muslim saint had been built there, and its brick-and-mortar remains still stood above ground.

To the soldiers' surprise, their shovels struck a stone wall. They 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. Under the pen name Chudomir, he happens 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 into a claustrophobic chamber 2.65 m wide and 3.25 m in height. It had a beehive-shaped cupola covered with even more impressive frescoes, one of the best preserved examples of ancient European painting ever discovered.

The tomb had been plundered in Antiquity, but on closer inspection, archaeologists discovered some bones from a man and a woman inside the tomb, and those of a horse outside, along with some pottery, fine gold ornaments and gilt clay rosettes used to adorn a tiara.

Kazanlak Tomb's murals are unparalleled and still inspire awe. The battling men in the corridor seem almost alive in their frenzied action, although it is not clear if they represent a battle won by the deceased owner of the tomb, or are acting out a commemorative event. In the burial chamber, three chariots chase each other, in an eternal circle, around the keystone of the cupola.

The tomb was discovered next to an abandoned türbe, or tomb, of a Muslim sage, Sıraca, the legendary founder of Kazanlak

It is the main frieze in the burial chamber that makes the Kazanlak Tomb a must-see. It depicts a man and a woman feasting, surrounded by musicians, servants and their beautiful purebred horses.

The Kazanlak frescoes depict something very similar to what Herodotus wrote about the Thracians' joyful death.

Of course, not everyone agrees with this interpretation. The beautiful face of the veiled woman who is sitting next to the wreath-crowned man, her white hand gently resting in his, is unmistakably sad. Why so? Is she mourning the death of her beloved husband? Or was she perhaps unhappy to be the favourite wife, the one "blessed" to accompany a powerful man in the afterlife?

Trying to put modern interpretations on ancient depictions is a mistake: those who lived millennia ago did not have our concept of art and would imbue deep meaning in the images that they created, particularly ones connected to religious beliefs.

An alternative explanation of the main scene in Kazanlak Tomb is that it depicts the funeral feast of a deceased noble who has been deified after his death. Another interpretation sees it as the mythological wedding of a deified man and the daughter of the Great Goddess of the Thracians, the creator of all the universe and the one who decided who would be king. The Great Goddess herself appears in the fresco: the highest of all the figures in the frieze, carrying a plate of pomegranates, the fruit associated with the afterworld.

Whatever the meaning of the frescoes, the talent of the artist is not in dispute. The tomb was probably painted by a Greek in the first half of the 3rd century BC. In the time of Hellenism, when the Greek fashion in luxury items, and also ideas, spread over a vast area in Europe, Asia and Africa, wealthy Thracians would often commission Greek artisans to make them gold jugs, expensive weapons and, obviously, funeral frescoes.

Kazanlak Tomb has fascinated people since it was discovered, and the list of scientific papers trying to solve its enigmas is impressive. Lyudmila Zhivkova, the daughter of Communist dictator Todor Zhivkov, was among them. Before becoming the de facto culture minister, she studied art history. In 1974, she published a book with excellent photography of the Kazanlak Tomb. It was translated, clearly for propaganda purposes, into English, Russian and Japanese.

In 1979 UNESCO put the Kazanlak Tomb on its World Heritage List as a "masterpiece of the Thracian creative spirit" and "a significant stage in the development of Hellenistic funerary art." Due to preservation issues, the tomb is closed to the public, but visitors can see an exact replica, erected just a few steps from the original.