Location: Bornholm Island Map
Constructed: 13th century
Hammershus (or Hammershus Castle / Hammershus Slot / Hammershus Borg)
is the largest medieval castle ruin in Northern Europe, located
dramatically on a 70–74 meter granite cliff at Hammeren on the northern
tip of the Danish island of Bornholm in the Baltic Sea.
Its imposing
position, with steep cliffs on multiple sides and panoramic sea views,
made it a formidable stronghold for centuries. Today, it is a popular
tourist site combining dramatic ruins, natural beauty, and rich history.
Construction and Early History (Late 13th–Early 14th Century)
The exact construction date remains debated, with sources varying
between the late 12th century and around 1300. Older accounts
suggested an earlier origin (possibly early 12th century) linked to
the Archbishop of Lund consolidating control over Bornholm via a
treaty with King Svend III Grathe. However, archaeological
excavations (notably around 2015) strongly indicate the main
fortress was completed around 1300, most likely ordered by
Archbishop Jens Grand (archbishop 1289–1302).
It was built
during a period of intense power struggles between the Danish Crown
and the Catholic Church.
Bornholm was largely under church
ownership, and Hammershus served as a strategic military and
administrative base for the Archbishops of Lund.
The castle
featured a core residence, a prominent "manteltårn" (mantle tower),
and an extensive ~750-meter perimeter wall enclosing the grounds. It
incorporated natural defenses like cliffs and freshwater springs.
Hammershus quickly became central to the Church-Crown conflicts.
It changed hands multiple times but often reverted to ecclesiastical
control. Notable royal conquests occurred in 1259, 1265, 1319, and
1325. After conflicts, it was often returned to the archbishops.
In 1362, after further warfare, King Valdemar IV Atterdag returned
it to the archbishop but secured a written agreement allowing the
Crown to reclaim it at will.
Medieval Power Struggles and
Expansions (14th–16th Centuries)
For roughly 500 years,
Hammershus served as the primary stronghold and administrative
center for Bornholm's rulers. It was repeatedly rebuilt and
expanded, reflecting ongoing fortifications amid regional tensions.
In the early 16th century, King Christian II took control in
1521–1522, exercising the earlier agreement. He used it to imprison
Bishop Jens Andersen Beldenak of Funen. Lübeck forces (of the
Hanseatic League) soon conquered it in the same period.
Bornholm
and the castle were pledged to Lübeck as debt security (1525–1575).
During this Hanseatic period, the fortress underwent its last major
expansions, including living quarters, a prison, chapel, and
strengthened defenses. Local forced labor and high taxes funded
this, sparking unsuccessful rebellions.
By the late 16th century,
after redemption from Lübeck, it became a Danish fiefdom.
Maintenance burdens led to gradual deterioration.
17th
Century: Wars, Rebellion, and Prison Use
Hammershus played roles
in major Nordic conflicts:
Torstenson War (1643–1645): Swedish
forces under Carl Gustaf Wrangel captured it in 1645, but it was
returned to Denmark in the peace settlement.
Second Northern War
(1655–1660): Denmark ceded Bornholm to Sweden in 1658. Swedish
occupation followed, but locals rebelled. Led by Jens Pedersen
Kofoed, rebels killed the Swedish commandant Johan Printzenskiöld in
December 1658. The Swedish garrison at Hammershus surrendered after
negotiations. Islanders then sailed to Copenhagen to reaffirm Danish
loyalty.
The castle served as a state prison in this era.
Most famously, in 1660–1661, King Frederik III imprisoned his
half-sister Leonora Christina (daughter of Christian IV) and her
husband Corfitz Ulfeldt for treason. They attempted a daring escape
down the walls and cliffs but failed.
Later, German Pietist
theologian, physician, alchemist, and occultist Johann Conrad Dippel
was imprisoned there from 1719 to 1724.
Decline, Demolition,
and Abandonment (18th–19th Centuries)
By the late 17th century,
evolving warfare (especially artillery) rendered medieval fortresses
like Hammershus obsolete. Defenses shifted to newer sites like
Christiansø and Rønne. The castle was abandoned as a stronghold in
1743.
Locals quarried stones and materials from the ruins for
building projects across Bornholm until 1822, when it was protected
as a national heritage site. Partial demolition occurred around
1750, accelerating its transition to ruins. Restoration and
preservation efforts began in the late 19th century (major work in
the 1880s–1900s), with ongoing maintenance since.
Modern Era
and Legacy
Today, the ruins are a major attraction on Bornholm,
with a visitor center offering exhibitions, panoramic views, shops,
and cafés. The site blends history with nature—nearby granite
quarries, Bronze Age petroglyphs, and dramatic cliffs. It has
inspired artists due to Bornholm's unique light.
Location and Setting
The castle sits dramatically on a rocky knoll
at Hammeren, the northern tip of Bornholm, approximately 74 meters (243
ft) above sea level on a steep cliff overlooking the Baltic Sea. This
elevated, isolated position provided exceptional natural defenses:
cliffs on the seaward side and a steep, winding land approach. Two
artificial lakes (created by damming) further strengthened the landward
defenses.
Overall Layout and Evolution
Hammershus evolved over
centuries from a relatively simple 13th-century stronghold into a
complex, multi-layered fortification reflecting advances in medieval and
early modern military architecture.
Initial Phase (late 13th/early
14th century): Built primarily under Archbishop Jens Grand of Lund
around 1300. The core was the Manteltårnet (Mantel Tower or Keep) — a
massive square tower — surrounded by a basic ring wall (curtain wall).
This formed the "base castle residence."
14th–16th centuries:
Expanded significantly with multiple rings of fortifications, additional
towers, gatehouses, and defensive enclosures. By the 16th century (under
Hanseatic influence and later Danish control), it featured four wings
around a large central courtyard, Renaissance-style bastions, and
enhanced outer defenses.
Key dimensions: The perimeter wall enclosing
the castle grounds stretches about 750 meters (2,460 ft) long. The
entire complex included residential quarters, storage, a great hall, and
extensive military structures.
The layout featured concentric
defenses: outer walls, intermediate defended areas, and the heavily
fortified inner keep area. This "box-like rooms surrounded by rings of
fortifications" design allowed defenders to fall back progressively.
Key Architectural Features
1. Manteltårnet (The Mantel Tower /
Keep)
The oldest and most iconic element. A massive, square tower
with walls nearly 2 meters thick. Originally 3 stories high with a
portcullis at the entrance. Floor levels are still visible from beam
holes in the walls. It served as the primary residence and last line of
defense. Later modifications turned parts into more comfortable lordly
quarters. The tower shows a mix of materials: lower sections in rough
local granite, upper in brick.
2. Curtain Walls and Towers
Thick
stone walls (granite base with brick upper sections) with multiple
towers and bastions added over time. The walls include putlog holes (for
scaffolding) and evidence of crenellations (battlements). Additional
towers were built in the 16th century.
Hammershus Castle Ruins
(Bornholm)
3. Entrance and Gatehouse
The main gate was originally
a square tower. A rampart wall was added in the 17th century. Access
involved crossing a fortified bridge over a 6-meter ravine (one of
Denmark’s best-preserved medieval fortified bridges), originally
featuring a wooden drawbridge section guarded by a bridge house.
Multiple defensive points along the approach could stall attackers.
4. Inner Structures
Central courtyard for daily life.
Storage
buildings (e.g., a two-story tax/storage house for grain and livestock).
Great hall and residential wings.
Cellars and foundations partially
carved into the bedrock.
Later additions included Renaissance
bastions for artillery defense.
Materials and Construction
Techniques
Primary materials: Local granite (rough, massive blocks
for lower walls and foundations) combined with red/clay bricks for upper
sections and later additions. This creates a distinctive two-tone
appearance in the ruins.
Construction exploited the natural rocky
terrain, integrating the castle into the cliff for added strength.
Thick walls (up to 2m) for resisting siege weapons, with strategic
placement of arrow slits, windows, and defensive openings.
Defensive Innovations
Hammershus exemplifies the transition from
early medieval tower-and-ring designs to more sophisticated concentric
and artillery-resistant systems. Features like multiple baileys (walled
enclosures), ravine bridges, and elevated positioning made it
exceptionally difficult to assault. It withstood numerous sieges and
changed hands between church, crown, Hanseatic League, and Swedish
forces.
Current State and Visitor Experience
Abandoned as a
fortress in 1743, it was quarried for stone until protected in 1822.
Partial restorations occurred in the late 19th/early 20th century.
Today, the impressive ruins allow visitors to explore the layout, climb
remaining walls, and see interpretive signage. A modern visitor center
(designed with concrete, local oak, and minimalist lines inspired by the
landscape) provides context without detracting from the historic site.