The Wisloujscie Fortress ('Twierdza Wisloujscie') is a fort carre located near the Westerplatte peninsula in Gdansk. The site was an area of strategic importance as it gave control of ships moving into and out of Gdansk. The fortress features various architecture styles and building materials, as through the centuries it was rebuilt after each enemy attack. The central point of the fortress is a round tower, which used to be a lighthouse. Since 1974 the Wisloujscie Fortress has been in the custody of the Historical Museum of Gdansk. The fortress is not only a military monument of great historical value, it is also one of the winter shelters for bats.