The Fraeylemaborg is a borg in the village of Slochteren in the Netherlands. At present the Fraeylemaborg is a historic house museum, which had 29,106 visitors in 2013.Fraeylemaborg is the most important of the borgen in the province of Groningen. These strong houses or keeps were built in the Middle Ages to store harvests and to protect their produce from robbers. Besides churches, these structures were the only buildings that used durable stone and masonry. In due time they grew to become centres of power and wealth. The Fraeylemaborg is located in the middle of the town of Slochteren which upon its discovery in 1959 gave its name to the largest gasfield in the world.