First enclosure

Thanks to old maps, documents and preserved remains, the layout of the walls of Brussels' first enclosure is perfectly known. The enclosure, which is four kilometers long, encompasses on one hand the first place of development of the city, the Saint-Géry island and the first port on the Senne river, and on the other hand the Treurenberg hills with the first Romanesque collegiate church of Saints-Michel-et-Gudule (11th century) and the Coudenberg with the ducal castle.

The enclosure, built with stones and earth, is made up of square-section pillars spaced about four meters apart and linked together by buried arcades topped with a wall pierced with loopholes. A second series of arcades supports the walkway protected by a crenellated parapet. The defense of the wall is supplemented by about forty towers and a large moat that could be flooded in certain parts of the city. Access to the city is provided by seven main gates and five secondary gates.