The island of Isegran is located almost in the heart of Fredrikstad on the Glomma River. It is notable for the fact that the first mention of settlements on its territory is found in ancient chronicles written long before the appearance of famous cities in Norway.

According to historians, the island was inhabited by fishermen and traders. There are no architectural or other material artifacts left from them. The oldest thing that has been preserved on the island is a castle of the 13th century. Why the castle was abandoned or who was its owner is unknown. However, the castle has come down to our days in a modified form: now it has a large mill and a mill house.

Besides, there is a mention of a fort on the island in the chronicles of 1287. The wooden castle belonged to Count Borgarsyssel, but, unfortunately, it was destroyed in the early fourteenth century. Today there is no trace of the former fortress, so it is difficult to even guess where exactly it was.

New military structures appeared on Isegran Island in the late 1600s. It was a large tower that became the foundation of the only military port in Norway during the Great Northern War.

Another interesting place for tourists is the embankment of the island. There is almost an open-air museum. Numerous boats look like old ones. But in fact, they are reconstructed vessels created by modern masters. The shipyards continue to build boats based on old traditions. Its workers are both professionals and volunteers. Guests have the opportunity to see how shipping has developed on the island of Isegran. Today the island is home to the Fredrikstad Museum. It regularly hosts exhibitions on naval and military subjects. Besides, there is a permanent exhibition dedicated to the history of the island, the city, and the whole country.