The 10 strongest castles in Germany

Königstein occupies a nine-hectare table of sandstone 240 metres above the Elbe, ringed by 1,800 metres of rampart set on cliffs up to 42 metres of sheer rock. A 152-metre well, the deepest in Saxony, meant no besieger could ever thirst the garrison out.

It was never taken. Its reputation was so absolute that Saxony kept its state treasury, and in wartime the Dresden art collections, behind its walls. In the Seven Years' War the elector could only watch from the summit as his own field army capitulated below at Lilienstein in 1756; the fortress itself was never assaulted. The only man ever to breach it was the chimney-sweep Sebastian Abratzky, who free-climbed the cliff for a wager in 1848.

Rheinfels was the largest fortress on the Middle Rhine, once five times the size of the ruin that survives, its rock honeycombed with casemates and mine galleries and a garrison that could swell to 4,500. High above St Goar, it was built to fight the artillery age, not just the age of the scaling ladder.

Its record backs the scale. It broke the League of Rhenish Cities in a siege lasting more than a year in 1255-56, held off Spanish troops in 1626, and in December 1692 became the only fortress on the left-bank Rhine to defeat Louis XIV, throwing back a French corps under Tallard numbering in the tens of thousands. It fell only when its own garrison handed it over without a fight to French revolutionary troops in 1797, who then quarried it for stone.

Burghausen is the longest castle in the world at 1,051 metres, a chain of six courtyards strung along a narrow ridge between the river Salzach and the Wöhrsee lake, each bailey sealed by its own gate and tower so an attacker had to win the ridge one enclosure at a time. Under Duke Georg the Rich it became the strongest fortress in the region and the treasury of the Bavaria-Landshut dukes; an inventory of 1533 counted 185 guns in its arsenal.

That depth of defence was rarely put to a serious assault, its length and river-and-lake setting deterred siege rather than invited it, and it was never stormed in its heyday, losing its front-line role only after the War of the Landshut Succession was settled in 1505. Real damage came only later, in the Napoleonic Wars.

The Imperial Castle crowns a sandstone ridge above the city, its Sinwell keep and a 50-metre rock-cut well anchoring a stronghold laced into Nuremberg's own famous walls, with artillery bastions added in 1538-45 as guns improved. It was a genuine imperial fortress, not a palace, but its 'never taken' reputation belongs to the walled city, not the castle.

The castle itself was stormed by Henry V after a two-month siege in 1105 and again under Lothair around 1130, and the burgraves' castle was burned by Duke Louis VII of Bavaria in 1420. In 1632 the armies besieging Nuremberg were wrecked less by fighting than by typhus. Air raids gutted the castle in 1945, and much of what stands is post-war rebuilding.

The Marksburg holds a near-vertical crag above Braubach behind a butter-churn keep, a ringed curtain, and the pointed artillery bastions the Hessian landgraves added when cannon arrived. It is famous as the only hill-castle of the Middle Rhine never destroyed, but that survival owes as much to its site and its luck as to any epic defence. It was besieged in the Thirty Years' War without being taken, and Louis XIV's castle-wreckers simply bypassed it in the 1690s rather than storm it; for long stretches it was garrisoned yet never seriously contested. Its one real battering came late and from modern guns, when American artillery across the Rhine damaged it in March 1945, and even then it was not captured.

Rebuilt after 1554 by Caspar Vischer into one of Germany's most powerful Renaissance fortresses, the Plassenburg wraps a hilltop above Kulmbach in massive bastioned ramparts designed to trade fire with cannon. The defences are formidable, but its war record is a fall, not a stand. In the Second Margrave War the town of Kulmbach was stormed and razed in November 1553, and the fortress, far stronger, still capitulated after roughly eight months of siege in June 1554. The rebuilt bastions fared no better in the end: a Bavarian-French army under Napoleon's brother Jérôme besieged and took it in 1806. A serious fortress, then, but one that was beaten more than once.

Trifels crowns one of three sandstone crags in the Palatinate Forest, a Reichsburg the empire trusted with its most precious things: the imperial regalia were kept here, and here Richard the Lionheart was held from the spring of 1193 after his capture returning from crusade. Its strength was as much reputation as masonry, a rock deemed secure enough to hold a king and a crown, and it was never taken in a famous siege. The building standing today, though, is largely a 20th-century reconstruction: after the Thirty Years' War the castle decayed to a quarried ruin, and much of the present fabric is Nazi-era work of 1938-42 and after, not medieval walls that ever withstood an assault.

Pfalzgrafenstein is a stone ship moored midstream, a pentagonal tower inside a hexagonal curtain on the Falkenau island in the Rhine below Kaub. Its real 'defence' was commerce: a chain across the narrows forced ships to stop and pay, and it added a gun bastion only in 1607. It was never destroyed, and it did once earn the reputation honestly, withstanding a 39-day siege in 1504 during the War of the Landshut Succession while the Hessians took heavy losses. But it was built to tax the river, not to break a determined army, and much of its survival owes to being a valuable customs post that no one had strong reason to level.

Hohenzollern's real power is its mountain: an isolated 855-metre cone rising alone above the Swabian plain, one of the strongest natural positions in Germany. The fortresses built on it fared less well than the site deserved. The first castle, called 'the crown of all castles in Swabia', was destroyed in 1423 after a siege of nearly a year by the Swabian League of imperial cities; its sturdier 17th-century successor was captured by Württemberg troops in 1634 and occupied by the French in 1744-45, then left to ruin. What stands now is neither of those: a Gothic-Revival family monument built in 1846-67 that has never fired a shot or faced a siege. Its rank here rests on the mountain and the record of what was built on it, not on the romantic silhouette.

Trausnitz sits on a hill above the Isar at Landshut, founded in 1204 and heightened over the centuries with extended walls and towers, but it grew into a Wittelsbach residence far more than a fighting fortress, a ducal seat turned Renaissance under Duke Ludwig X, later serving as barracks, prison and hospital. Its position watches over the town, yet it has almost no siege record: it was not stormed in the War of the Landshut Succession that convulsed the region in 1503-05, and no major assault against it is recorded. Genuine and old, but the least-tested stronghold on this list, more palace on a height than a castle built to break armies.