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.

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.”