The Heuneburg is a prehistoric Celtic hillfort located near the Danube River in Hundersingen, close to Herbertingen. It lies between the cities of Ulm and Sigmaringen in Baden-Württemberg, southern Germany, near the modern borders of Switzerland and Austria. It is considered one of the most important early Celtic centers in Central Europe, especially during the Iron Age Hallstatt culture period. In addition to the fortified citadel, there are remains of settlements and burial areas that date back over several centuries.

The citadel measures about 300 by 150 meters. It was built on a hill that rises steeply 40 meters above the Danube River. The site is located in the middle of a fertile river plain, surrounded by rolling hills. During the Iron Age, the Heuneburg is believed to have controlled an area larger than 1,000 square kilometers. This area included other hilltop settlements, villages, roads, cemeteries, and places used for gatherings or religious activities.

The settlement has been called "the oldest city north of the Alps." It is also linked to the Celtic city of Pyrene, which was mentioned by the ancient writer Herodotus.

Discovery and excavations

The site was first noticed in the 1820s. In 1882, Eduard Paulus [ de ] recognized its importance and correctly identified it as a prehistoric fortification. He thought the lower fortifications were from the medieval period. Some nearby burial mounds were opened in the 19th century.

Occasional excavation work on the citadel started in the 1920s. In the 1930s, the Hohmichele mound was studied (see below). A planned excavation program happened from 1950 to 1979, led one after another by Adolf Rieth [ de ], Kurt Bittel, Egon Gersbach [ de ], and Wolfgang Kimmig [ de ].

Since 2003, the Heuneburg has been a key focus of a research project about early Celtic centers, supported by the Deutsche Forschungsgemeinschaft. New excavations began in 2004.

History

The Heuneburg is best known as an important early Celtic center from the 7th to 5th centuries BC. However, it was occupied at other times in its history.

The first settlement on the site dates to the Middle Bronze Age (15th to 12th century BC) during the Tumulus culture period. At this time, the main plateau was protected with a large ditch and bank, including a wooden wall. The settlement was abandoned at the start of the Urnfield period. This abandonment did not seem to involve violence. During the Urnfield period, a burial area existed in the location of the later Südsiedlung (see below).

The citadel was reoccupied and refortified around 700 BC. Nearby areas, such as Alte Burg and Grosse Heuneburg, were also occupied at the same time. The Heuneburg complex grew quickly, and by 600 BC, it was one of the key centers of power and trade in Celtic/Halstatt southern Germany. Major changes in the site’s layout occurred around that time. Before 500 BC, the site suffered a major destruction, followed by a second period of growth and another destruction in the 5th century BC. It was once believed the Heuneburg was abandoned by the La Tène period, but recent evidence does not fully support this. The combination of a strong fortified site, elaborate burials, specialized crafts, and trade in valuable imported goods places the Heuneburg among a small group of similar important early Celtic sites, called Fürstensitze (see below).

The Heuneburg’s strategic location led to some activity during the Middle Ages, though there was no permanent settlement at that time.

The Celtic citadel

The main plateau, covering two hectares (4.9 acres) on a mountain spur, is located 40 meters above the Danube River. This natural high ground was easy to defend and became the center of important settlements and fortifications during the Celtic period. It measures 150 by 300 meters (490 by 980 feet) and is the most noticeable landmark in the area. From around 700 BC, this location was the heart of a large settlement.

The main settlement on the citadel changed many times over its history. Houses were built using wood and daub, and fortifications were mostly made of wood and earth. These structures were replaced often, leading to more than a dozen distinct phases of occupation that span at least 250 years.

The plateau was fortified starting around 700 BC. At first, the fortifications were made of a classic Celtic wood-and-earth wall (called a murus gallicus), which was replaced regularly.

Around 600 BC, this wall was replaced by a unique structure not seen elsewhere in Celtic Europe at that time. A limestone foundation supported a sun-dried mudbrick wall about 4 meters (13 feet) high, likely topped by a roofed walkway, making the total height 6 meters. The wall was covered with bright white lime plaster, which was repainted often to protect the mudbrick from weather damage. Towers extended outward from the wall at regular intervals. This wall was probably very visible in the area, as seen in modern reconstructions. No other mudbrick buildings are known from Celtic Central Europe at this time. This structure likely imitated similar walls in the Mediterranean region.

The wall remained in use for about 70 years, much longer than earlier and later wood-and-earth walls, which needed frequent rebuilding. After a fire around 530 BC, the settlement was again protected by a murus gallicus until another destruction in the 5th century.

The fortification had two large gates. One was on the west side, connecting to outer settlements, and the other was on the east, likely leading to a steep road that reached the Danube River (and possibly a harbor).

The citadel had a regular system of streets and houses. After 600 BC, the settlement was reorganized, and homes were built more densely and uniformly than before. The houses at Heuneburg were unusually large and elaborate compared to other settlements of the time. The uniform buildings likely served as homes and workshops. Evidence shows an active metal industry, including a bronze workshop in the southeast corner of the citadel. After the destruction of the mudbrick wall in 530 BC, the layout changed. Workshops were moved to the north, and a very large house (14 by 30 meters [46 by 98 feet]) was built in the southeast corner. This house is sometimes thought to be the home of a local leader.

The Heuneburg site has many artifacts showing it was a wealthy place. It functioned as a center for local production and long-distance trade. Finds include a full bronze workshop, many Greek vases (fragments from about a dozen Greek pots), and imported materials like tin and amber. Much of this exotic material dates to after 530 BC. There was also a local tradition of making painted and decorated pottery, such as incised or stamped designs.

Settlements outside the citadel

Recent discoveries near the Heuneburg have provided important information about the size of the settlement. It seems the citadel was only a small but important part of the larger settlement most of the time.

The Aussensiedlung, also known as the exterior settlement, was located downhill to the west and northwest of the citadel. It was likely occupied from the 7th century (Hallstatt period) to the 5th century BC. This area appears to have been a separate settlement with walls for protection. The Aussensiedlung covered up to 100 hectares, much larger than the citadel itself. It seems to have included separate areas with fences or wooden walls, each containing a main house, storage spaces, and land for farming. Each area may have been used by an extended family. Experts estimate that between 5,000 and 10,000 people lived in the Aussensiedlung. However, the land area could not have produced enough food for such a large population. The Giessübel mounds, which are built on top of parts of the Aussensiedlung, must have been created after the settlement was abandoned.

The Südsiedlung, located further south, appears to have been similar to the Aussensiedlung in size and time period. It may have been connected to the Aussensiedlung.

Large fortifications discovered in the 19th century were once thought to be medieval in origin, but they are now known to be part of the Celtic settlement. These structures have been damaged by erosion and farming over time. A system of three large walls and ditches, stretching several hundred meters, surrounded and divided the area to the west of the Heuneburg. Since these walls were built on top of homes in the Aussensiedlung, they must have been constructed later. Some parts of the walls are still standing at a height of over 6 meters, and the ditches were originally 7 meters deep.

Recent excavations uncovered a large gate in the westernmost wall. This gate measured 8 by 12 meters and was a strong structure. Its walls were made of limestone stones held together with a special clay mixture, and both sides were covered with finely cut limestone blocks. Like the mudbrick wall on the citadel, this gate is unusual for the Celtic world and resembles architecture found in the Mediterranean region at the same time.

Iron Age cemeteries

Several burial areas surround the Heuneburg. These areas include groups of earthen tumuli or burial mounds. More than 50 such monuments are known in the area. Not all have been excavated. Some date from the Hallstatt period, but most are probably La Tène. The relationship between important fortified sites and elaborate burials is also known from other important Celtic centers, like Glauberg oppidum and grave, the Hochdorf Grave near the Hohenasperg settlement, and the Vix grave near Mont Lassois.

The Giessübel cemetery is located 500 meters (1,600 feet) northwest of the Heuneburg. It was built on top of the then abandoned west part of the Aussensiedlung. By the 19th century, four mounds remained here, each measuring about 50 meters (160 feet) in diameter and 7 meters (23 feet) in height. First excavations were undertaken in the 19th century (mounds 2 and 3), but more systematic work took place between the 1950s and 1980s.

This mound contained a rectangular wooden chamber (3.5 by 5.5 meters [11 by 18 feet]). Its main occupant was a man aged around 50. There were also remains of two women. It had been robbed in antiquity, but modern archaeological finds nevertheless included weapons, gold and bronze attachments for garments, and some amber plaques that probably once adorned a couch imported from the Mediterranean. Twenty further burials were later placed in and on the same mound.

Grave 4, also robbed, contained a single individual, accompanied by the remains of metal attachments from a wooden chariot.

A cluster or necropolis of burial mounds, the so-called Hohmichele Group, is located 3.5 kilometers (2.2 miles) west of the Heuneburg. It consists of at least 36 burial mounds. The group is named after its largest mound, the Hohmichele. It is located near Altheim (Biberach district). Most of the mounds are not visible anymore due to natural erosion and ploughing. The 14 or so that remain are located in forests.

The first excavation of the main Hohmichele mound took place from 1936 to 1938, directed by Gustav Riek as part of the research program of the SS-Ahnenerbe. Only about a third of the mound was removed during that project; the central burial chamber was located. After the war, from 1954 to 1956, Siegwalt Schiek undertook further excavations.

With a diameter of 85 meters (279 feet) and a height of over 13 meters (43 feet), the Hohmichele is one of the largest Celtic tumuli in Europe. Excavation has mainly concentrated on its central and eastern portions. The mound was used from the late 7th to the late 6th century BC. Thirteen burials were located within the mound, several of them accompanied by grave offerings. The mound was restored to its original dimensions in 1960. Today, it is visible as a vegetation-covered landmark in a small forest clearing. A modern war memorial is located on its summit.

The center of the mound contained an oak-built main chamber (Grave I), built on the original ground level. It measured 5.7 by 3.5 meters (19 by 11 feet) and was about 1 meter (3 feet) high. This grave, containing a man and a woman, had already been plundered shortly after the burial. The remaining finds, reflecting its original riches, include horse trappings, nearly 600 glass beads from a necklace, pieces of amber, and fine gold threads that were originally part of a brocade-like fabric. The floor had been covered with cowskins. A central mound, 5 meters (16 feet) high and 40 meters (130 feet) in diameter, covered this chamber.

Twelve meters (39 feet) southeast of the central chamber and about 2.2 meters (7 feet 3 inches) above the old ground surface lay an unplundered wooden chamber (Grave VI). It measured 3 by 2.4 meters (9.8 by 7.9 feet) and was 1 meter (3 feet) high. This grave also contained a man and a woman. Their equipment included a four-wheeled chariot with trappings for two horses, bronze eating and drinking vessels, a quiver with 51 iron arrowheads, an iron knife, and many amber and glass beads (from necklaces), including 2,300 green glass beads. The woman had been laid in the chariot, the man on the floor. The bronze vessels were placed by their feet and heads. There were also remains of embroidered fabrics.

Grave IX, a so-called pyre grave, was located 1 meter (3 feet) above VI. Its occupant was a woman who had died between 18 and 30 years of age, her remains accompanied by two bronze armlets and over 20 pottery vessels with incised and stamped decorations and red paint.

Six further graves (II-V, VII, VIII) were inhumations. Twenty-two fireplaces found within the mound are probably connected to cult activity. Some or all of them may represent funerary pyres.

Interpretation and significance

The Heuneburg and its nearby monuments are among the most important places from the early Celtic Iron Age in Central Europe. This site should be studied along with other important centers of that time, called Fürstensitze, which means "princely seats" in German.

The Heuneburg settlement shows important changes in early Celtic society. Around 700 BC, wealth and people began to gather in smaller areas, and this trend grew faster after 600 BC. Differences in wealth are seen in both homes and burial sites, showing the rise of social classes. For example, in 2005, archaeologists found the burial of a 2-year-old child near the Heuneburg with imported Etruscan jewelry. Since a young child could not have earned such items, the child must have been born into a wealthy family. This suggests that political power may have also been centralizing. The Heuneburg and nearby area could not produce enough food for their own people, meaning they likely relied on support from a larger surrounding region. Specialized workshops and areas for craftspeople developed, producing goods beyond local needs.

The term Fürstensitz, used to describe places like the Heuneburg, has been criticized by some archaeologists, such as Manfred Eggert from the University of Tübingen. Critics argue that the term might give a misleading view of power structures and overlook more complex realities.

Around 700 BC, other hilltop sites appeared near the Heuneburg, possibly similar in size and population. Most of these were abandoned by 600 BC, around the time the Heuneburg was reorganized. Some believe the Heuneburg grew powerful enough to draw people away from other sites. The Hohenasperg settlement, about 100 km north of the Heuneburg, may have been involved in the Heuneburg’s destruction after 500 BC, but there is no clear evidence for this. Recent studies suggest the Heuneburg’s abandonment is uncertain.

Older ideas that the Heuneburg’s citadel was destroyed violently and that the site was abandoned after this are now less certain. While the mudbrick fortification was likely destroyed, it is unclear if this was due to war or internal problems. The area’s economy improved after this event, suggesting the site may not have been completely destroyed. The second destruction, in the 5th century BC, is even more unclear. Some think the fires may have been accidental. At this time, the Heuneburg plateau and nearby areas were mostly abandoned, but smaller settlements and burial activity continued, possibly showing a shift in where people lived and how society changed.

Some researchers believe the growth of Celtic cultures between the 7th and 5th centuries BC was linked to a warm climate. A milder climate would have allowed better farming, supporting larger populations and more complex societies. When this warm period ended, populations may have declined, and economic systems could have collapsed. The decline of places like the Heuneburg and the Celtic migrations of the 4th century may have been connected to these changes.

The Heuneburg’s importance is tied to its location near major trade routes. Situated north of the Alps and along the Danube River, it had access to land routes from Italy and southern France, as well as river routes to the Balkans and Black Sea. The site was involved in trade between northern and southern Europe, exchanging luxury goods, wine from the south, and items like amber, metals, leather, and fur from the north. The influence of Mediterranean cultures, such as Greek and Etruscan, is seen in the Heuneburg’s mudbrick fortifications and newly discovered ashlar masonry.

In the mid-5th century BC, the Greek historian Herodotus briefly mentioned a Celtic city called "Pyrene" in his writings. Since the Heuneburg was a major center before this time and located in the area described, it may have been the city Herodotus referred to.

Museums

The Heuneburgmuseum is located in a restored barn that was once part of the old monastery in Heiligkreuztal, Hundersingen. The museum's displays show how important the site was and include some of the original artifacts found there and at nearby burial sites.

In recent years, an open-air museum was built on the Heuneburg plateau. This museum has recreated several homes and a section of the ancient mudbrick wall.

Some of the items discovered in the Hohmichele grave are on display at the Württemberg State Museum in Stuttgart.