EDINBURGH, Scotland — On Calton Hill, overlooking Edinburgh, stands Scotland’s National Monument. A colonnade of classical stone pillars modeled on the Parthenon in Athens, it’s grand, inspiring — and unfinished, ever since the money to build it ran out two centuries ago.
It’s a fitting image for the country as seen by independence campaigners, who hope voters will finish Scotland’s incomplete journey to statehood by backing separation from Britain in a referendum on Thursday.
Polls suggest the outcome will be close. For many people south of the Scottish-English border, the idea that Scotland might leave the United Kingdom has come as a recent shock. But it has been decades, even centuries, in the making.
‘‘I’ve always felt we could run ourselves. We used to, years ago,’’ said David Hall, whose job is winding the clocks on some of Edinburgh’s most famous structures, including the Nelson Monument on Calton Hill.
He adds an often-heard sentiment: ‘‘We’ve always been treated as second-rate up here, by down south.’’
Scots have always felt different from their southern neighbor, whose population today is 10 times Scotland’s 5.3 million. The Romans never managed to conquer Scotland, and remnants of Hadrian’s Wall still stand along the northern limit of their empire.
Scotland and England fought skirmishes and wars throughout the Middle Ages, and the exploits of Scottish heroes William ‘‘Braveheart’’ Wallace and Robert the Bruce form part of the national mythology.
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Britain — the country uniting England, Scotland and Wales — is a relatively recent development. England and Scotland have shared the same monarch since 1603. Political union came a century later, in 1707 — to the dismay of some Scots.
‘‘Many felt it had been imposed upon them by a bullying England and that Scottish politicians had been bribed into submission,’’ said Christopher Whatley, professor of Scottish history at Dundee University.
‘‘That narrative ... has pulsed through the Scottish body politic through the centuries.’’
But for a long time, in the eyes of most Scots, the Union worked. For almost three centuries, Britain was a global success story, carving out a vast empire. Scots were among the leading players, as colonists, soldiers, administrators, engineers and intellectuals. The 18th-century ‘‘Scottish Enlightenment’’ produced thinkers including economist Adam Smith, philosopher David Hume and poet Robert Burns.
In the 19th century, Glasgow and other Scottish cities thrived on shipbuilding and manufacturing that powered the empire.
For many Scots, their junior status in the union rankled. But some historians argue that the nationalist notion of wee Scotland oppressed by its domineering big brother is nonsense.
Prime Minister David Cameron shares that view, arguing in a recent newspaper column that the United Kingdom was behind many of the great advances in history.
‘‘When the world wanted representation, we gave them democracy,’’ he wrote. ‘‘When they wanted progress, we had the Scottish enlightenment and the industrial revolution.’’
In recent decades, however, the bonds holding the United Kingdom together have frayed. In the decades after World War II, Britain lost its empire. The economic upheavals of Prime Minister Margaret Thatcher’s era in the 1980s — which saw the collapse of industry, widespread privatization and mass unemployment — alienated many Scots and weakened a shared sense of Britishness.
Edinburgh University historian Tom Devine says the surging sense of Scottish identity that has led the country to the cusp of statehood ‘‘is partly based on myth and history’’ stretching back to Bruce and Wallace and the medieval wars with England.
‘‘But that is only one thread in a much more complex tapestry of identity formation,’’ said Devine, who supports independence. ‘‘The key triggers now are more political and social.’’
Scottish writers and artists have helped fuel a new confidence, which has coincided with increasing political autonomy. In 1997 Scots voted to set up a parliament in Edinburgh with substantial powers over health, education and other sectors.
Since then the Scottish National Party under leader Alex Salmond has abandoned tartan-and-haggis cultural cliches to make a political and civic case for separation.
Salmond argues that independent Scotland will be a ‘‘Northern Light,’’ a beacon of progressive social policies and economic dynamism.
In 2011 Salmond’s SNP won a majority in the Scottish assembly, with the promise of a referendum on full independence.
Ever since, the No side has argued that Salmond’s sunny vision of the future is based on unrealistic assumptions, but has struggled to present a positive alternative.
While anti-independence campaigners express affection for Scotland and the Union — the equivalent of a spouse shouting ‘‘Don’t leave!’’ — much of their argument has centered on the economic risks of separation.
This is not the first time in Scottish history that dreams of statehood have run up against cold economic reality.
In the 1690s, the Kingdom of Scotland tried to secure its world status and economic future by setting up a trading colony in Panama.
The venture was a disaster. Most of the 2,500 colonists died of starvation and disease, thousands of Scots who had invested lost their life savings, and the country was left so indebted that it turned to England for financial aid, and political union.
The result was the Kingdom of Great Britain — the country that will end if the Yes camp prevails this week.
Whatever Scottish voters decide, Whatley — who says he’ll be voting No — thinks there is one positive parallel to that time three centuries ago.
‘‘The Scottish people are more engaged with politics than at any time in Scotland’s history,’’ he said. ‘‘You saw that before the Union in 1707. I think we are seeing exactly the same engagement and passions on both sides now.”