Historically, the Fort of Janjira (Murud-Janjira) in India and the Fort of Murud-Janjira are often cited as the most impregnable due to their unique marine location. Built on an oval rock off the Arabian Sea coast, the fort remained unconquered for over 450 years, despite repeated attacks by the British, Portuguese, and the Maratha Empire. Another top contender for the "most impregnable" title is the Citadel of Qaitbay in Egypt or the Fort of Kumbhalgarh in India, which boasts the world's second-longest wall (36 kilometers long and wide enough for eight horses to ride abreast). In Europe, the Fortress of Königstein in Germany is legendary for never being captured in battle due to its position on a high sandstone plateau. What makes these forts truly "impregnable" is a combination of geographic elevation, self-sustaining water and food storage systems, and "dead-fall" traps that made a direct assault suicidal. Even with modern siege engines of their respective eras, these forts typically only fell through long-term starvation or betrayal from within, rather than a breach of their massive stone walls.