I've got this idea for an exhibition. The centrepiece would be a light spectacular, a ring of 150 searchlights beaming straight up into the darkness like columns. There'd be heroic statues, too, and projections of formation movement, and uniforms and flags. The gist of the show would be that a bit of history, normally seen in political and military terms, actually offers a rich visual culture. My working title is REICH: Power and Style in Germany 1933-45. I'm hoping that maybe the V&A will be interested.

I don't see how we can fail, with the talents involved. The films of Leni Riefenstahl are recognised classics. The sculpture of Arno Breker is much maligned, and overdue for reconsideration. As for the architect Albert Speer, who staged that light show for the 1934 party rally, he's a kind of genius. Of course, we wouldn't be skirting round the difficult issues raised by the display. Clearly there are aspects of the period that will seem distasteful to a contemporary audience. But, hey: that's civilisations. Look at the Aztecs. Systematic human sacrifice, sure – but what buildings, what artefacts! Or am I missing something?

Well, what are the rules here? A Nazi visual-culture blockbuster is clearly intolerable. An Aztec blockbuster is clearly not. There was one at the Royal Academy of Arts in 2002. It made no bones about the bloodletting involved: there were sacrificial knives on view, blood cups, skulls, ample evidence of the sun-oriented death-cult. It drew record-breaking crowds. Some people found it disturbing. Nobody said it should have been banned.

Download the new Independent Premium app Sharing the full story, not just the headlines

When it comes to gauging the exhibition-worthiness of a culture, it's a question of balancing up various factors. You measure its evil against how long ago it happened and its artistry. With the Aztecs, time and wonder outweigh butchery. With the Nazis, it's too recent, too abominable.

So, how about the Romanovs? Next week, an exhibition opens at the V&A with an elaborate title: Magnificence of the Tsars: Ceremonial Men's Dress of the Russian Imperial Court, 1721-1917. It offers some of the most extravagant examples of formal court wear, from Peter the Great to Nicholas II. And if that's your kind of thing, it's certainly going to be magnificent. There'll be coronation mantles, heralds' livery, headdresses, spurred boots, dress coats, postilions' jackets, cushions, gloves and gunpowder flasks – everything embroidered and inlaid with gold.

This wardrobe isn't just lavish for lavish's sake. It is a blazing sign of authority. Here is a culture where intricacy of workmanship and opulence of materials are – as so often – the expression and instrument of rule. The visual is integral to the political. As one witness to the coronation observed, it was "a spectacle incomparable with anything else in its gripping beauty and intrinsic meaning ... for those few hours alone it is possible to experience at once all the might, all the greatness of Russian power". Visitors to the show can hope to get just a bit of that shiver of awe.

But were they such great guys, those tsars? A bit slow to abolish serfdom, not really pioneers in the field of civil liberties – and not all that long ago, either. Is this the kind of celebration they deserve? Set off autocracy, the secret police and the prison camps against a marvellously adorned pair of boots, its turnover tops shaped like lions' heads: how do the sums work out exactly?

The usual answer, I suppose, is: just grin and bear it. If you like fancy goods, a little bit of oppression is the price you probably have to pay. High craft and high art have always been complicit with big power, and if big power isn't always very nice, well, get over it. Or if you can't, then try to believe that art and craft can rise above it. The great work, even possibly the great boot, transcends its circumstances.

Maybe it does. You might think that at least we'd hope it does. But looking at the way exhibitions go, it seems the opposite is true. Art's complicity with power is not something art-lovers resist. On the contrary, they embrace it. Getting a frisson of power – military, dynastic, ecclesiastical – is part of the point of being an art-lover. Exhibition organisers know this.

Consider the titles they devise, and consider this list of words: Magnificence. Majesty. Splendour. Grandeur. Glory. Golden. Triumph. Treasure. Any show that has one of those words in its title is playing on power-appeal. Or simply look at the shows, and the effect on attendance when it's a total-culture spectacle – when the exhibits come with massive historical force behind them. The force doesn't even need to be all that wicked to have this effect. It just needs to be big, an empire, a civilisation, an epoch.

Go to Byzantium 330-1453 at the Royal Academy now – Byzantium, heir to the Roman Empire, medieval superpower, centre of the Eastern Church. Move through its crowded and semi-darkened galleries, glinting with metal work, gleaming with gold-leafed images. There is a great deal of stuff. There's a load of finely wrought gold and ivory. There are a great many intensely eyeballing icons. The exhibits individually may tell many different stories, but altogether they communicate the greatness of a culture and a faith.

Here, opulence and craftsmanship are the material signs of untold spiritual riches. If they could have got Hagia Sophia itself over from Istanbul, they would have. Unfortunately, it's fixed to the ground and bigger than the RA. But what the show wants to convey is what some 10th-century visitors to that great church said, trembling: "We knew not whether we were in Heaven or on Earth."

True, in these shows, there's a tension between the pleasure of being overwhelmed and the duty of being informed. But being overwhelmed is the decisive thing, and what overwhelms is always a compound of visual power and some other kind of power. Think back to last year's The First Emperor at the British Museum. It only had on display a small deputation from the Emperor's vast funerary terracotta army, but managed to summon up the power of ancient China, and its mad despot who wanted to guarantee his eternal life.

Or think back 35 years to the ancestor of these shows, the British Museum's Treasures of Tutankhamun – or to last year's cheap-and-cheerful repeat version at the O2, Tutankhamun and the Golden Age of the Pharaohs. It's another case of a supreme ruler-god, and masses of human artistry and human lives being dedicated to his afterlife. If you want a wonder of the world that gets the crowds rolling up, you can't beat a slave economy.

The British Museum's current show puts a bit of perspective on this phenomenon. Babylon – Myth and Reality looks like it should be another one, another homage to a magnificent and merciless conquest-regime and its visual glories. But they haven't got enough of the big stuff to do that job. In Berlin, there's a full-size reconstruction of the Ishtar Gate, with its walls of deep blue brickwork molded with lions and fantastic creatures. In London, we have a 1:1,000 scale model.

Art-power-trippers won't get much directly out of it. The show is intelligently and lucidly instructional. There's some ancient history. There's much on the legends surrounding Babylon: Tower of Babel, Hanging Gardens, Nebuchadnezzar eating grass, Jewish captivity, Belshazzar and the Writing on the Wall, the Whore of Babylon. And there's contemporary history, about the archaeological site, under Saddam and then under Coalition occupation, both destructive in different ways – and the urgent need now to reconserve.

But that moral is complicated, because the Babylon story is mainly a story of falling down. It's a cycle of magnificent construction and destruction. All the images of Babel invite us to revel in the grandeur of collapse and ruins. It's a power spectacle by another means – as Albert Speer, the Nazi architect, knew. "Ruin-value" was one of his building principles. An edifice should look good newly up, and also, centuries later, tumbled down. In both states, it would declare the might behind it.

And though I trust there will be no Nazi blockbuster show for a while yet, it seems to me that the spirit of Speer presides over the grand culture exhibitions we already have. Just as he did, these shows understand too well an awkward fact about us. How we love to be overpowered. How our visual pleasures are part of a general power fix. Tsars, kings, pharaohs, emperors, patriarchs, leaders: small wonder we're so often putty in their hands.

Magnificence of the Tsars, Victoria & Albert Museum, London SW7 (020-7942 2000), 10 December to 29 March. Byzantium, Royal Academy of Arts, London W1 (0870 848 8484), to 22 March. Babylon, British Museum, London WC1 (020-7323 8181), to 15 March.