The fortified town of Weesp lies on the crossroads of three former lines ofdefense: the Old Dutch Water Defense Line, the New Dutch Water Defense Lineand the Defense Line of Amsterdam. Since 1996 the Weesp fortresses of Ossenmarkt and Uitermeer, as part of the Defense Line of Amsterdam, have beeninscribed on UNESCO’s World Heritage List. The strategic significance of Weesp asa fortified town can be found at various places. Already in the seventeenthcentury the town was part of the Old Dutch Water Defense Line. The invadingFrench were successfully stopped by this line in 1672.

Soon after this thefortifications of Weesp were expanded. Of the eight planned bastions four wereconstructed and still exist. In the nineteenth century, when Weesp became partof the New Dutch Water Defense Line, the fortifications had to be adapted. In 1845 the Uitermeer Fortress was built and in 1861 the Ossenmarkt Fortress wascompleted. By the end of the nineteenth century, during the construction of theDefense Line of Amsterdam, the fortified town of Weesp was included in this.