When Lahnstein was granted town status, it obtained, apart from court and market rights, the basis to build town fortifications. The town wall, fortified with 16 towers, formed an approximate rectangle with a total length of about 1280 meters. In front of the town wall, which was eight meters high and had a roofed parapet walk and a surrounding town moat, was the outer ward with a lower front wall. One had to pass six gate towers, drawbridges and foregates to get into the town.
Six towers and about 350 meters of wall have been preserved to the present day. The Bürgerturm (Citizen's Tower, Hintermauergasse 1), the Hexenturm (Witch Tower, Salhofplatz), the Pulverturm (Powder Tower, Hintermauergasse 29), the Salturm (near Kirchstraße 6, in the garden of the Catholic Rectory), the tower in the Hintermauergasse 25, the former town gate in the Brunnenstraße, the wall segment between Hintermauergasse 15 and 17 and the wall segments west of the railway tracks belong to the overall complex which was begun in 1324.
The construction of the northeastern corner of the old town fortifications began in the year 1324. The octagonal tower, 26 meters in height and built of quarry stone, stands amidst a 97m-long preserved segment of the old town wall.
On the ground floor is the former prison of the town Lahnstein. Corkscrew stairs lead up to the second floor with the jury hall. Formerly used as a guardroom for the soldiers guarding the tower, today, it is used for formal receptions by the municipal administration, and for weddings. The tower also accommodates the museum of the town Lahnstein which documents Lahnstein’s rich history with coats of arms, seals, and documents.
The round tower, 26 meters in height and built of quarry stone, used to mark the southeastern corner of the town fortifications. The entrance to the tower was located high above the parapet walk of the town wall and was only accessible by ladder. The attack side is decorated with a sandstone relief showing Johann the II of Nassau, Archbishop of Mainz, kneeling before a crucifix. Archbishop Johann completed the tower in 1411.
The only preserved town gate with a square gate tower built of quarry stone with crenelation and stair tower. On the tower are high-water marks from 1882 until 1988. When the railway was built, the Kihrstor was integrated into a railway underpass; the former town wall forms the railway embankment on the Rhine side, on a length of 203 m.