Kristianopels fästning

Kristianopel (in Danish Christianopel) was founded on the orders of Christian IV of Denmark on the island of Korsaskär near the historic town of Avaskär in 1599.

During this period Denmark built a number of border fortifications for protection against Sweden’s ambitions to become a great power, and this was the easternmost. Its importance as a border fortress diminished once Blekinge became part of Sweden in the Peace of Roskilde in 1658.

Source: Wikipedia