The first fortifications with earthen walls are already mentioned in 1427. Under the direction of Adriaen Anthonisz, the city and castle were given a new wall with jumps in 1577. In order to be able to arrange inundations of the environment, the locks came to lie within the fortifications. In 1629, the inundation system was improved and in 1677, bombed walls were installed.
Originally laid out in 1678 and renewed in 1854, the hollow bear (at Herengracht 1) with monks and three culvert openings. The estuary received earth batteries on both sides in 1799. The 1786 to 1874 low-walled Amsterdamsestraat 3-5, which were later plastered from 1784, served as barracks and then until 1923 as homes for army personnel and as an infirmary. The form. Amsterdamsestraat 26 waiting room, a neoclassical one-storey building from around 1825 with a brick arcade on simple pillars, was part of the Amsterdamse Poort (demolished 1910). From 1854 the fortress became part of the New Dutch Water Line and in 1892 Muiden with Weesp became part of the Defense Line of Amsterdam. All this resulted in a further strengthening and expansion. In 1854 two ravelins came into being in the western and one in the eastern moat. On the other side of the harbor mouth, the western battery (Westzeedijk) dating from 1799 was extended in 1852 with an oval three-tiered tower fort with moat and enclosure (fortified 1875-'77). The fortification was further enlarged and improved in 1874 -76 by the construction of bombproof spaces, depots, watchhouses and the like on the ramparts and the bastions. This includes, among other things, the Muizenfort (Naarderstraat approx. 1874), built on the Ravelijn, built in 1853, on the Naardertrekvaart. In addition, the Kazernestraat 10 (1876) barracks were built with earth cover, exercise square and officers' houses (Kazernestraat 6-8, 12-14).
The west wall, which was dismantled and defaced in 1923, was restored in 1955 by raising and planting. The concrete casemates Muiden-West (near Weesperbinnenweg 7) and the canon casemate Muiden-Oost (near Zuidpolderweg 4) date from 1931. The round radar tower (Rijksweg 81) was built by the Germans around 1943 to detect aircraft and is now part of an office building.
