The 10 strongest castles in Spain

The Castle of Cardona commands its town and the salt mountain that made its lords rich from a steep hill, its Romanesque and Gothic core stiffened in the eighteenth century with angled bastions and casemates built to trade fire with artillery.

It was never taken by force. In 1711 a Bourbon army some fifteen thousand strong bombarded it for over a month before a relief column drove the besiegers off, and when Cardona finally capitulated in September 1714 it was the last Catalan stronghold still holding out, and then only on negotiated terms, not by storm.

Gormaz is the largest Caliphal fortress in Europe, a walled crest some 390 metres long, ringed by 28 towers and split by an internal moat into a citadel and a vast bailey with cisterns. Greatly enlarged under Caliph al-Hakam II in the 960s on a high promontory above the Duero, it anchored the Middle March and served as a base for raiding north.

That scale was tested. In 974-975 the fortress held against a combined army under Sancho of Navarre, Garcia of Castile and Ramiro III of Leon until the Cordoban general Ghalib relieved it in the summer of 975. As the frontier shifted it changed hands repeatedly, and by 1087 El Cid held it as lord of Gormaz.

Sagunto sprawls for nearly a kilometre along a hilltop ridge above the Valencian plain, a palimpsest of Iberian, Roman, Moorish and later walls enclosing a chain of separate plazas, commanding ground rather than a single keep.

Its fame rests on 219 BC, when Hannibal besieged the Iberian town for eight months before storming it, the spark of the Second Punic War, though almost none of the walls standing today are that old. It saw war again at the Battle of Saguntum on 25 October 1811, when Marshal Suchet routed Blake's relief army and the French took the castle.

The Alcazaba climbs its hill in concentric rings, a double circuit of walls, bent gateways and repeated inner barriers, while a fortified corridor, the Coracha, linked it to the higher Gibralfaro castle so troops and supplies could move under cover during a siege. Enlarged by the Nasrids in the fourteenth century, it ranked among the strongest Moorish fortresses in Spain.

It was not impregnable. In 1487 the Catholic Monarchs besieged Malaga for roughly four months; the garrison under Hamet el Zegri held out behind the walls until a naval blockade and starvation forced surrender on 18 August 1487, after which much of the population was enslaved.

Santa Barbara caps Mount Benacantil, a rock rising some 166 metres straight above Alicante and the sea, and is one of the largest medieval fortresses in Spain. The sheer crag does much of the defensive work, with walls and towers in three tiers climbing the summit and the approach funnelled up a single hard ridge.

The Moorish stronghold fell to the Castilian prince Alfonso, later Alfonso X, after a siege of several months, taken on 4 December 1248, the feast of Saint Barbara that gave it its name. It was fought over again in the War of the Spanish Succession, held by an Allied garrison until Bourbon engineers sprang an enormous mine beneath the rock in 1709 and forced its surrender.

Loarre is reckoned the finest Romanesque fortress in Spain, and its strength is as much geological as built: it sits on a limestone spur high above the Hoya de Huesca, a natural pedestal that made a formal assault almost pointless. King Sancho Ramirez raised the fortified core around 1070 as a forward base against Muslim-held Bolea, and a later outer curtain studded with round towers wrapped a second line around the rock. Its record is quiet precisely because of that position. It was a springboard for offensive campaigns rather than a place enemies chose to besiege, and it was never stormed, though that owes as much to the site deterring attack as to any epic defence.

Calatrava la Vieja guarded a Guadiana crossing on the Toledo frontier, a large fortified enclosure ringed by a water-fed moat, with an albacar for livestock and a coracha reaching down to the river. Taken from the Moors by Alfonso VII in 1147, it became the cradle of the Order of Calatrava, founded here in 1158 to hold a place the Templars had judged untenable. Events proved them partly right: after the Christian rout at Alarcos in 1195 the Almohads stormed Calatrava and put its defenders to the sword, and only the victory at Las Navas de Tolosa in 1212 secured it for good.

Almodovar sits on an isolated hill above the Guadalquivir west of Cordoba, a genuinely commanding site of Roman then Umayyad origin dating to around 760; it surrendered to Ferdinand III in 1240 and later served as a royal fortress and treasury. But the crenellated silhouette seen today is largely a modern creation, between 1901 and 1936 the Count of Torralva rebuilt it in romantic-medieval style under the architect Adolfo Fernandez Casanova, using thousands of cubic metres of fresh stone. The hill was always strong ground, but the walls now standing never withstood a medieval siege in their present form.

Coca is the masterpiece of Mudejar brick military architecture, and its defences are genuinely sophisticated: two concentric square wards with polygonal corner towers, walls around two and a half metres thick, projecting emplacements pierced for firearms, all wrapped in a broad, deep moat. Built from about 1453 for the Fonseca archbishops, it was designed for the artillery age, but it sits on flat ground with no natural height, leaning entirely on its ditch, and was raised as much for display and residence as for war. Its record bears that out: it never endured a serious siege, and its strength on paper was never proven by an attacking army.

Belmonte crowns the hill of San Cristobal above its town, a hexagonal fifteenth-century castle enclosing a triangular ward and studded with cylindrical towers, built from 1456 for Juan Pacheco, Marquis of Villena, to display his power as much as to defend it. It was fitted for early artillery, but its story is that of a grand seigneurial residence rather than a fighting fortress, it saw little real war, later declined into a prison and then a ruin, and was remodelled in 1857 as a romantic retreat for the Empress Eugenie de Montijo. As a genuine stronghold it is the weakest here: handsome and well-sited, but never proven under siege.