The National Monument is a structure on Calton Hill in Edinburgh, Scotland, inspired by the Parthenon in Athens. It was never completed, apparently due to lack of funds, and for this reason it was once popularly known as 'the pride and poverty of Scotland' or 'Edinburgh's Folly', but the folly of the National Monument seems pretty trivial next to the Scottish Parliament building down the road, which cost £430 million - more than ten times its original budget, and ten thousand times that for the National Monument* - for something far less attractive. In my experience most people call it 'the Acropolis' these days, which annoys pedants because the real Acropolis is the hill the Parthenon sits on, not the building itself, and anyway that's not its name. Wikipedia calls it 'The National Monument of Scotland', presumably to avoid confusion with various other National Monuments, but as far as I can tell that's not officially its name either.
Calton Hill rises dramatically just to the East of Princes Street, Edinburgh's main drag, and while it can't quite match Edinburgh Castle on the other side, the drama is greatly enhanced by what they did get round to building of the National Monument - a series of enormous stone steps leading up to a platform with a series of twelve towering Doric columns, capped by an architrave. The view from the platform is breathtaking, among Edinburgh's best; you can see all of the northern part of the city spread out beneath you, everything that's not hidden by one of Edinburgh's spectacular extinct volcanoes, Castle Hill and Arthur's Seat. Beyond Leith you can see right out across the Firth of Forth, and on a clear day you can see the Fife shore, all the way over on the other side. I know of nowhere better to witness a Scottish sunset.
The view of the platform is also pretty good, and the monument acts as one of the main performance areas for Edinburgh's Beltane celebrations. It is here that the needfire is lit, with sparks and dry brush, and once the new fire is burning, the May Queen makes her entrance over the platform's top, between rows of processional drummers whose rhythms represent the heartbeat of the ceremony. More ritual performances take place up there later in the night.
The monument was conceived as a memorial to the Scots who died in the Napoleonic Wars. The decision to have a specifically Scottish monument was significant, and contentious. To quote Historic Scotland's Listed Building Report:
The situation was likened to that of Athens under Roman rule, subsumed into a wider empire, but seen as stronger in terms of intellect and culture. Edinburgh was therefore beginning to be seen as Athens to London's Rome, a claim which was strengthened by Scots achievements during the Enlightenment, and the extensive adoption of the Greek Revival style of the architecture of Edinburgh in the early nineteenth century.
There was a foundation ceremony for the monument in 1822, during a visit from George IV (who did not deign to attend) and an appeal was launched for £42,000 for the building of it. By 1826 £15,000 had been raised, designs had been drawn up by leading architects C.R. Cockerell and W.H. Playfair, and building started in earnest. The original plans included catacombs and pylons in addition to the colonnade we see today, but after three years that £15,000 was exhausted, no more money was forthcoming, and construction ceased.
*Adjusted for inflation, the Parliament building still cost a hundred times as much as the budget the National Monument failed to raise.