The 8 strongest castles in Austria

One of Europe's largest fully preserved medieval fortresses, Hohensalzburg crowns the Festungsberg some 506 m above Salzburg, a stronghold roughly 250 m long whose outer bastions were begun in the 16th century and finished in the 17th against the Ottoman threat.

In more than nine hundred years it was never taken by force. Its one real test came in the German Peasants' War of 1525, when miners and townsfolk besieged Prince-Archbishop Matthäus Lang and failed to break in. It opened its gates only in 1800, a bloodless surrender to General Moreau's French, never to an assault.

Enthroned on a steep volcanic neck 482 m above the south-east Styrian plain, Riegersburg is the largest castle in Styria and, by the mid-17th century, one of the strongest in the country. Baroness Katharina Elisabeth von Galler completed its defences between 1637 and 1653: kilometres of curtain wall, a chain of gates and bastions, and two dry moats climbing the basalt rock.

Barely 20 to 25 km from the Ottoman frontier, it earned a reputation in the Turkish Wars as 'the strongest fortress in Christendom' and sheltered thousands of country people behind its walls. No attacker is recorded as ever taking it, though that 'never conquered' status rests on its unbroken reputation rather than on any single documented repulse. Its only fall was administrative: Soviet troops occupied it on 8 May 1945.

Kufstein commands a rock above the Inn on the old Tyrol-Bavaria frontier. Its defining work, the great round Kaiserturm, is a squat artillery tower with walls metres thick, but it was raised in 1518-22, after the fortress's most famous defeat, to rebuild a stronghold that heavy guns had proved could be broken.

That defeat came in 1504, in the Landshut War of Succession. The Bavarian captain Hans von Pienzenau refused Maximilian I's summons and, by tradition, had the cannon-dust swept from the walls with brooms in mockery. Maximilian answered with his two giant bombards, 'Weckauf' and 'Purlepaus'; after three days the walls lay in ruins, the garrison surrendered, and Pienzenau and several companions were beheaded.

Hochosterwitz rises on an isolated dolomite crag some 160 m above the Carinthian plain, visible for 30 km. Its defence is a single idea taken to an extreme: a 620 m approach spiralling up the rock through fourteen fortified gates, each independently held, built for Georg von Khevenhüller between 1570 and 1586 as Ottoman raiders ravaged the region, a system regarded as unique in castle-building.

By local tradition no attacker ever passed the fourth gate, the Engelstor, and the castle was never conquered. That reputation, though, is legend rather than battle-record: the celebrated tale of the defenders slaughtering their last ox and hurling it over the wall to feign plenty comes from the medieval chronicler Jakob Unrest, and no documented siege of the fourteen gates survives.

Hohenwerfen stands on a 155 m rock pillar, 623 m up, above the narrow Salzach valley at Werfen, a natural choke-point the fortress was built to control, backed by a keep, curtain walls and later bastions, and used by Salzburg's prince-archbishops as stronghold, armoury and state prison for the best part of nine centuries. Its hardest years came in the German Peasants' War, when in 1525 and again in 1526 rebel farmers and miners moving on Salzburg burned and badly damaged the castle; it was repaired and never permanently lost, and no successful storming of the fortress is recorded.

Forchtenstein sits 511 m up above the Wulka valley in northern Burgenland, its core a 50 m keep, the 'Black Tower', over a deep rock-cut pit, approached only by a rough, easily blocked track. From 1622 the Esterházy princes rebuilt the crumbling castle into a serious frontier stronghold under the architects Simon Retacco and Domenico Carlone. Its distinction is negative but real: through the Ottoman incursions of the 16th and 17th centuries, including the campaigns around the 1683 march on Vienna, Forchtenstein was the one castle in its region the Turks never took.

Aggstein clings to a narrow rock ridge roughly 300 m above the Danube in the Wachau, a site its 12th-century builders thought impregnable and one perfectly placed to levy toll, or plunder, from river traffic; its most notorious lord, Jörg Scheck vom Wald, 'Schreckenwald', preyed on shipping in the 15th century. The natural position was formidable, but the castle itself was taken again and again: besieged and captured in 1230-31 in Hadmar III's revolt against Duke Frederick II, once more in 1295-96, seized in 1463 and surrendered in 1476, then razed by the Ottomans in 1529. It never recovered, and stands a ruin.

Landskron occupies a rock cone 658 m up, north-east of Villach, a commanding Carinthian hill-site the Habsburgs bought in 1355 and rebuilt as a stronghold. But it earned its later fame as a residence, not a fortress: after Christoph Khevenhüller acquired it in 1542 he remade it in lavish Renaissance style, and no siege or capture appears in its record. Its end came not in war but by weather, a lightning strike in 1812 gutted the castle, which was never rebuilt and fell to ruin. It ranks last here as the least siege-hardened of the group, more palace on a hill than fortress.