Landsfort Herle was a fortification with moat. It was probably built by the counts van Ahr-Hochstaden (also referd to as Here van Are). The name Landsfort (‘fort of the land’) comes from the fact that the fortification come under the responsibility of the land. In the 13th century Heerlen, and thus also Landsfort Herle, come in to the possession of the Dukes of Brabant, the Landsfort was (re)built by the Dukes of Brabant in 1244.
The wall is believed to be one of the oldest still recognisable in the Netherlands, part is now being excavated. A marquette of the fort was constructed from a map form 1787 found while the Pancratiuskerk was heavily reconstructed in the 1960s. The fort had three gates and had two towers (the bell tower of the church and the Schelmentoren, both with 2 metre thick walls).
In the roof of the church were little rooms for the inhabitants of Heerlen to take shelter in case of hostilities, unfortunately these rooms were destroyed when a, supposedly German, bomb hit the church at New Year's Eve 1944/1945.
References:The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.