Skytsborg Tower—today widely called Blackbeard’s Castle—was built in 1679 as a Danish military watchtower on Government Hill.
Rising above Charlotte Amalie Harbor, it formed part of a defensive network with Fort Christian and Schmidtsbjerg Tower (Bluebeard’s Castle), allowing soldiers to identify approaching ships long before they reached port.
With six-foot-thick masonry walls and commanding 360° views, Skytsborg was the first line of defense for one of the busiest harbors in the Caribbean.
Originally called Baggaertsbjerg, after master mason Carl Baggaert who designed it, the tower has carried multiple names over the centuries:
Baggaertsbjerg
Kaier Tower
Fogarthy’s Castle
Skytsborgtårn (“Sky Tower”)
Blackbeard’s Castle
It is one of only five National Historic Landmarks in the U.S. Virgin Islands and the only surviving 17th-century fortified tower in its original form.
Skytsborg is an extraordinary example of early Danish Caribbean military engineering.
Native Augite Andesite (“blue bitch”) stone
Coral and limestone
Spanish red brick framing windows and the entrance
Walls 53 inches thick at the base, tapering to 40 inches
Originally plastered and whitewashed
31 ft 6 in tall
20 ft diameter at base, narrowing slightly toward the top
Four interior levels, originally separated by wooden floors
Nine to thirteen brick-lined gun ports per level, arranged in radial patterns
From the top, defenders could spot enemy fleets or pirate ships across miles of open sea. Signal fires relayed urgent messages to Fort Christian.
The tower’s interior was designed entirely for surveillance and defense:
Stone floor
Nine gun ports
Brick-lined elliptical arched entrance
Thirteen gun ports
One larger embrasure added in 1688 to mount cannons aimed at the harbor
Circles of gun ports
Final level once opened onto a gun platform
In the 19th century, a small wooden observatory structure was added to the roof by a private astronomer. It was later removed to restore the tower’s historical appearance.
Though local legend ties the tower to Edward Teach (Blackbeard), there is no historical evidence he ever lived here.
Historians note Blackbeard primarily operated from Port Royal, Jamaica, and would not have sought refuge in a Danish military tower actively trying to capture pirates.
Still, the name “Blackbeard’s Castle” became permanent—blending centuries of fact, rumor, and storytelling into a single iconic landmark.
In the mid-1900s, the surrounding property was incorporated into a hotel complex, though the tower itself was never structurally altered.
By contrast:
Schmidtsbjerg (Bluebeard’s Castle) was heavily modified—large windows cut into its walls and rooms added.
Trygborg Tower at Fort Christian was demolished in the 1870s.
Skytsborg is the only tower to survive unmodified, retaining its full original shape, materials, and defensive footprint.
From its construction in 1679 to its status today as a National Historic Landmark, Skytsborg Tower has witnessed:
Danish colonial rule
Pirate threats and naval battles
The growth of Charlotte Amalie into a major port
U.S. acquisition of the Virgin Islands
Modern tourism and preservation efforts
Standing at the tower today, you stand in the same vantage point that soldiers used centuries ago—looking over the harbor, watching ships pass, and imagining a world where signal fires and cannon blasts shaped the fate of St. Thomas.
From Skytsborg’s platform you can see St. Thomas, St. Croix, and Vieques on a clear day.
