context: Svartholm Sea Fortress is a sea fortress off the coast of Loviisa, built as a base for the Swedish Navy and to secure the border with Russia. Colonel Augustin Ehrensvärd designed it as a regular bastion fortress. The construction of Svartholm began in 1748 and was completed in key parts during the 1760s, but never fully completed. [1]
question: When was Svartholm Sea Fortress built?
answers.text: began in 1748 and was completed in key parts during the 1760s, but never fully completed