Kastelholma (Castle)

The origins of Kastelholma Castle date back to the 14th century, with its construction year estimated around 1384. Its first documented mention appears in 1388 in a treaty by Queen Margarethe I of Denmark, who incorporated a significant portion of her inheritance from Bo Jonsson Grip into the castle. In the 15th and 16th centuries, Kastelholma experienced its heyday, serving as a strategically important defensive point, even being referred to as the “Key to Sweden” in 1525, underscoring its importance for the defense of Stockholm. King John III held his deposed brother Erik XIV captive here until the autumn of 1571. During the civil war, the castle was repeatedly destroyed in 1599 by the battles of King Charles IX. The damage was only repaired in 1631, but in 1745, the castle almost completely burned down. The ruin was abandoned in the 1770s, but today, large parts of the castle have been reconstructed.

Kastelholma is located in the municipality of Sund in the Åland Islands (Ålands skärgård) on Ahvenanmaa (Åland) in Finland, at an elevation of approximately 9 meters above sea level.

Visitors can explore Kastelholma Castle today as a museum. Large parts of the former structure have been reconstructed and are accessible.

• Bomarsund Linnoitus (Fortress) (Ruins), approx. 9.0 km away
• Penningby Castle (Castle), approx. 99.8 km away
• Ekebyholm Castle (Castle), approx. 109.5 km away
• Rånäs Castle (Castle), approx. 111.1 km away