This unique fortified building is the most expansive system of fortifications in Central Europe, which is situated both in the Slovak Republic and in Hungary. The oldest part, the so-called Old Fortress, was built in the 16th century on the site of the former mediaeval castle. In the 17th century it was expanded by the so-called New Fortress. After the two devastating earthquakes in the 18th century, the Fortress lost its military character. However, due to the military expedition of the French Emperor Napoleon I, it was restored, upgraded and expanded to the largest fortification system of the Austro-Hungarian Empire at the beginning of the 19th century, which, if necessary, could accommodate 200,000 soldiers.
The military function of the Fortress was preserved long after the fall of the Monarchy. In 2003, it became the property of the Town of Komárno. Since then, it has been gradually restored and its gates are open to the general public all year round.