A town on the island of Walcharan in the southwestern Netherlands, probably founded as a refuge for the Flemish population in the times of Viking raids. Many of this type of refuge were probably planned by Baldwin of Flanders in the 890s. Middleburg consisted of a simple circular fortress with a massive rampart and ditch. The symmetry of these early fortresses is fossilized in the street plan of modern Middleburg. Excavations show the town was founded about 1000, from which time it has developed as a regional center.