Edinburgh Castle Is One Of The UK’s Most Beloved Landmarks, But It’s Hiding A Startling Secret

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If ever you visit Scotland’s capital, you’ll more than likely take a stroll along the city’s principal thoroughfare: Princes Street. As you walk amidst the skirls of the bagpiping buskers and the clang of the trams, your eyes will be attracted southwards and upwards. There, looms a massive blackened pile of rock and atop sit the magnificent walls and towers of Edinburgh Castle. But what won’t be immediately apparent is the complex’s tightly held secret.

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Edinburgh Castle is set at the eastern end of the Royal Mile – a street which runs through the winding lanes and passages of Edinburgh’s Old Town. Some of the buildings such as John Knox House date from as long ago as the 15th century. At the Royal Mile’s western end lies Holyrood Palace, which was once the home of Scottish royalty and is still the Queen’s official residence in Scotland today. 

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Below the castle, Princes Street is the northern boundary of Edinburgh’s New Town. However, “new” is relative in this case since the splendid Georgian houses there date from the 18th and 19th centuries. When the New Town was built, its wide, handsome streets were seen as an antidote to the teeming slums of the Old Town nestled to the south around the Royal Mile.

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We’ll come back to the unexpected secret that Edinburgh Castle and the Castle Rock it stands on harbor, but first let’s explore the history of this majestic Scottish monument. There’s archeological evidence of a settlement on the Castle Rock – which stands 430 feet above sea level – dating right back to the Iron Age some 2,000 years ago.

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Excavations around Castle Rock in the 1990s revealed evidence of ancient human habitation including Roman brooches and pottery. This suggests that whoever was living at the site was trading with the Romans who occupied England and parts of southern Scotland at the time. Researchers raised the intriguing possibility that even as early as the first or second centuries A.D. there may have been a broch – a type of hill fortress – on Castle Rock.

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In fact, the Greek scholar Ptolemy gives some support to the possible existence of a fort in a map he drew in the second century A.D. It shows a place called Alauna – a name meaning “rock place” which could refer to Castle Rock. History goes offline at this point up until sometime around 600 A.D. when an epic poem from Wales called Y Gododdin, mentions “the stronghold of Eidyn.” And researchers assume this references a fortress on Castle Rock. 

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Fast-forwarding again, we come on to firmer ground with the reign of King David I who held something resembling a parliament at Edinburgh Castle for 11 years from 1139. And indeed the oldest building still standing in Edinburgh Castle, St. Margaret’s Chapel, dates from that era. The simple stone chapel commemorates St. Margaret of Scotland – who is said to have died at the Castle in 1093.

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Over the centuries of the Middle Ages, Edinburgh Castle was often involved in the bitter and bloody conflicts which periodically broke out between the Scots and the English. In fact, the latter first took control of the Castle as early as 1174. The Scottish king, William, was captured by the English at the Battle of Alnwick in northern England. And the deal to release him included handing over the keys to the castle.

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The English hung on to the Castle for 12 years until 1186 when William married an English noblewoman – Ermengarde de Beaumont – in a union approved of by the English King Henry II. As part of the wedding dowry, the castle was returned to the Scots. It would remain in their hands for more than a century until the outbreak of the First War of Scottish Independence in 1296.

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This First War of Independence started when England’s Edward I invaded Scotland in 1296. After subjecting Edinburgh Castle to volleys of cannon fire for three days, the English again took control of the stronghold. They then stole many of its treasures and billeted a 325-strong garrison there. But the Scots clearly had their eyes open for any opportunity to seize back their property.

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An operation to retake Edinburgh Castle came in 1314; by that time, Edward I had been dead for seven years and the English grip on Scotland had loosened. In March 1314 the 1st Earl of Moray, Thomas Randolph led a bold surprise assault under cover of darkness allegedly with just 30 men. The element of surprise proved decisive and after scaling the walls and overwhelming the defenders, the Scots reclaimed possession.

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Robert the Bruce, who was Scotland’s king at the time, ordered the castle’s fortifications to be demolished in order to prevent the English from re-occupying it as a stronghold. A few months later, the castle’s position was secured when Robert the Bruce decisively defeated the English at the Battle of Bannockburn. But Scotland’s fight for independence was far from over, and the structure would soon play its part in the struggle for freedom again.

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The English next attacked Scotland in force under the leadership of King Edward III – invading their northern neighbor in 1333. This ignited the Second War of Scottish Independence, and two years later the English again captured Edinburgh Castle. This time they strengthened its defenses and hung on to their prize until 1341.

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As in 1314, a well-planned attack to retake the castle was again led by a Scottish nobleman. In this case the leader was Sir William Douglas, Lord of Liddesdale, and he was quite prepared to use deception to achieve his goal. Subterfuge was essential since the English had strengthened the fortifications so that scaling the walls was no longer feasible.

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Douglas ordered some of his men to dress as if they were harmless merchants, ostensibly delivering supplies to the 100 English soldiers occupying the castle. But when the supposed merchants’ cart reached the entrance, it stopped in the gateway and prevented its closure. Douglas had hidden men near the gates and they now poured into the castle. The entire English garrison was then put to the sword.

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For the time being, the long years of intermittent war between Scotland and England finally came to an end in 1357 with the Treaty of Berwick. Scotland’s King David II, Robert the Bruce’s son, was now in control of his country. Peace allowed the rebuilding of the castle and additions to its structure, including David’s Tower, not actually completed until after David’s death in 1371.

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Edinburgh Castle now enjoyed a period of peace and was established as Scotland’s most important center of governance. However, peace with England did not bring an end to drama within the castle walls – which now provided a stage for Scotland’s often brutal domestic politics. And a particularly horrific example of those came in 1440 at the Black Dinner.

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The Scottish king at the time was James II who had succeeded to the throne in 1437 after the assassination of his father, James I, by discontented Scottish barons. The new ruler was just six years old and there was bitter rivalry among the nobility for control of the child King James II.

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Matters then came to a head in November 1440. Two of Scotland’s principal nobles, the Earl of Douglas, aged 16, and his younger brother were invited to Edinburgh Castle. The Douglas clan was one of Scotland’s most powerful. And after dinner had been served to the Douglases the two were both beheaded. No wonder the events of that evening became known as the Black Dinner.

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Another notable incident illustrating the rough and ready politics of the time came in 1479. It involved the Duke of Albany, Alexander Stewart, brother to King James III. Suspecting his brother of conspiring against him, the king had him locked up in David’s Tower. But Albany escaped by plying his guards with drink then clambering out of a window and down a rope.

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Albany made his way to France and then England – where he formed an alliance with King Edward IV against his brother James III. Apparently, power politics apparently ran thicker than blood in those days. In 1482 the Duke now invaded Scotland accompanied by an English force of 20,000 and besieged Edinburgh Castle – entrapping his brother king within its walls.  Fortunately for all, after several weeks the matter was settled by negotiation.

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As so often in years gone by, in 1570 Scotland was riven by bitter rivalries between competing factions among the country’s nobles. In 1567 Mary Queen of Scots had been compelled to relinquish the throne in favor of her infant son James VI – who was born in Edinburgh Castle a year earlier. Once again Scotland had a child king, but this one had not yet even reached his first birthday.

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The Earl of Moray of the time, James Stewart, was appointed as regent and became Scotland’s ruler. He in turn put Sir William Kirkcaldy of Grange in charge of Edinburgh Castle. However, Moray was killed in 1570 by James Hamilton of Bothwellhaugh – who was still loyal to Mary. The former Queen – still regarded by some Scots as the rightful monarch – was by now living in England and was effectively a prisoner of Queen Elizabeth I.

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After Moray’s death, Grange, Keeper of the Castle, switched sides and shifted his support from the infant James VI to the exiled Mary. The Earl of Lennox replaced Moray as regent and in May 1571 his forces moved to besiege Edinburgh and its castle. There followed what came to be known as the Lang Siege – “lang” simply being the Scots word for long.

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As minor clashes between the opposing forces rumbled around Edinburgh Castle, Grange sat tight and took the opportunity to strengthen his stronghold. Mary’s supporters appealed to France for help, while the regent Lennox looked to England’s Elizabeth I for support. Probably wisely, the English and French declined to get militarily involved in the unseemly morass of Scottish politics.

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However, Elizabeth did send diplomats to help with negotiations between the Mary and James factions. Perhaps surprisingly, they had some success and a truce was agreed in the summer of 1572. Under its terms, Grange held on to the castle while Lennox kept control of the city. But the truce was time-limited until January 1, 1573.

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No sooner had the truce expired than Grange opened fire on the good people of Edinburgh from the castle walls. He had at his disposal some 40 cannons; but fortunately for the city’s people, Grange had limited supplies of ammunition and only seven men who could operate the guns. Nevertheless, many houses were destroyed and a number of citizens were killed or maimed.

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Grange succeeded in strengthening the hostility of Edinburgh’s citizens towards him and his followers by raiding the town, burning down 100 houses and killing more people. It was clear something had to be done. Edinburgh’s population was under attack from ruthless men holed up in the city’s own castle. And it was up to the new regent, the Earl of Morton to act.

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Morton had succeeded his predecessor Lennox in 1571 after the latter had been shot dead in a skirmish near the Scottish city of Stirling. The regent prepared to besiege Edinburgh Castle by poisoning its well and digging trenches around the perimeter. In April 1573 Elizabeth at last sent a 1,000 strong force from England with 27 cannons to help in the capture of the castle.

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The attackers peppered Edinburgh Castle with around 3,000 cannonballs – destroying David’s Tower and other parts of the battlements. Grange, threatened by insurrection from his own followers, finally surrendered on May 26, 1573. A vengeful Morton had the rebellious Keeper of the Castle publicly hung at Edinburgh’s Mercat Cross on the Royal Mile. And we can assume that Edinburgh’s sorely tired citizens heartily approved of this punishment.

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Edinburgh Castle sustained much damage during the two years of the Lang Siege and Morton now started a program of reconstruction. But the future held yet more trouble for Scotland and the castle. England’s Oliver Cromwell, the Puritan who took power after Charles I’s beheading, invaded the country in 1650. The complex was again besieged, this time for three months, and then captured.

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Cromwell then died in 1658 and the monarchy was restored two years later. Charles II now came to the thrones of England, Scotland and Ireland. The three crowns had been united in 1603 when Scotland’s James VI also became James I of England when he succeeded Elizabeth I. Amazingly, this happened without any major conflict. James, already king of Scotland, was simply the legitimate dynastic inheritor of the English and Irish thrones.

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Charles II ordered that a military garrison should now secure Edinburgh Castle – an arrangement that was maintained until 1923. And many years would pass before the castle again came under threat. Danger returned in 1745 as the Second Jacobite Rebellion erupted in Scotland. This was an attempt by Charles Edward Stewart – better known as Bonnie Prince Charlie – to oust George II, King of England Scotland and Ireland.

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Stuart, with his ragged but fearsome army of Highlanders, succeeded in taking Edinburgh, but the castle’s garrison refused to surrender. Stuart’s force had no heavy guns to make an effective assault on the well-defended complex and abandoned the attempt to take it in favor of marching on England. Ultimately, the rebellion was comprehensively defeated at the Battle of Culloden in 1746.

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And that final flourish from the Jacobites was the last time that Edinburgh Castle was threatened by military force. Part of it would go on to hold prisoners of war from various conflicts were held over the years. But by the 19th century the castle’s significance as a military stronghold was superseded by its role as a cherished national symbol for the Scots.

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Edinburgh Castle is now Scotland’s most popular tourist attraction with well over two million visitors in 2018. Now tourists can peruse the formidable castle walls and ramparts with their panoramic views of the Scottish capital and the surrounding landscapes. But probably very few of those casual visitors know about the startling secret we alluded to earlier.

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The fact is that the blackened basalt rock that Edinburgh Castle is built on was once a raging volcano. We’ve reviewed the human history of the complex itself, but the full story of the Castle Rock stretches back to a time long before humans or anything resembling them existed. The sheer cliffs the castle stands on appeared some 350 million years ago during the Carboniferous era.

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A volcanic pipe sliced through the sedimentary rock around the site of the castle. And it left behind an incredibly hard stone formation called dolerite – a kind of basalt. When glacial erosion later occurred, the Castle Rock was left standing proud as the land around it was ground away by ice. So visitors to the Edinburgh Castle are actually standing above an extinct volcano.

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And if you should ever happen to walk along Edinburgh Castle’s lofty ramparts, cast your eyes to the east. There you’ll see two other prominent hills with rocky outcrops both of which are also the remains of extinct volcanoes. The closer of the two is Calton Hill, which is easily recognizable from the bizarre Victorian folly at its summit.

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A little further east from Edinburgh Castle, the hill known as Arthur’s Seat is visible, with its dramatic curtain of sheer cliffs known as Salisbury Crags. Geologists believe that Calton hill is actually part of the same volcano that centered on Arthur’s Seat. So the fact is, when you’re in Edinburgh, you’re never far from a volcano.

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