Being a historian has its good days and its bad days. The good ones are almost intoxicatingly exciting - when you press the walls of the cave and they give way, revealing a room full of treasure that has been lying undisturbed for centuries. Those are the days when you get to feel like Indiana Jones and it all feels worthwhile.

Then there are the bad days. Forget Harrison Ford; think Charlton Heston at the end of The Planet of the Apes and his blood-curdling wail: 'What have we done ?????!!!!!'

I had a protracted spell of that when I was in Istanbul a week ago. You don't need me to tell you what a fabulous city it is, layer upon layer of gloriously rich history. The buildings, the stories, the gossip, the tragedy, the hope. It's the past in full Technicolour™

So here's the problem. As I walked through the city on the first morning, I saw a group of tourists gathered with cameras and smartphones whirring at a location I was not familiar with in the shadow of the majestic Haghia Sophia. I strolled over expectantly - new things are always being found in Istanbul: perhaps they were examining a piece of mosaic floor; or inscription; part of a column perhaps? I flicked into Indiana Jones mode. Here was something exciting; a discovery of some kind; perhaps I could even offer a few pearls of wisdom to the tourists.

They were taking pictures of a kitten.

Fair enough. Except that it was a pattern everywhere I went. By Fethiye Camii: a group of tourists were snapping a cat. By the column of Constantine: Italians taking photos of cat rolling about with another cat. At the Milion - the Hyde Park Corner of Constantinople: small tour group holding smartphones up to take shot of cat sleeping, or possibly dead. At the German Fountain: large group standing next to guide holding umbrella not listening to description of the Kaiser's visit to the city, but marveling at cat chewing on what appeared to be some kind of meat product. By the baths of Zeuxippos: twenty tourists taking photo of cat sitting on Vespa.

It was like a joke: no one seemed interested in the wonders of the city, these crown jewels of civilization. It was not once, twice or a few times, but everywhere. Ignore the rich tapestry of history that Istanbul has to offer. Come to look at its cats and kittens instead. Jeepers. Aww - look at the kitties. For 91 days.

I wandered round in something of a fog. I'm the one with the problem, I told myself. What's wrong with me: why am I more not more interested in the little furry four-legged friends; what's so great about these marvels of human creation? History, the tourists of Istanbul seemed to be saying: it's all in the past. Who cares?

You should be forgetting The Alexiad and fiendishly complicated middle Byzantine literature like the letters of Michael Psellos; read A Street Cat named Bob, which topped The Times and The Sunday Times best-seller lists. Give it's smash hit follow-up a go: Bob. No Ordinary Cat, currently shifting copies by the shedload. Forget The Odyssey by Homer - read Homer's Odyssey, the New York Times Best Seller about a man and his blind wonder cat. And then, on the flight home, it was like Groundhog Day: I opened The Times and found page three dominated by a story about: cats.

I've a few theories about all this - ranging from the decline of the west to the failure of modern education that makes learning and curiosity seem like work; from shortened attention-spans to the overwhelming opiates of fast-food, TV and pleasure-seeking. We might not have a clue about Syria, Iran, Russia, China and all those other places where it helps if you actually know something about their past and present. But we're good to go if war breaks out in the feline world: key in what does cat think into Google and you get 5 billion hits.

Cue mid-life crisis on the streets of the Queen of Cities, as Constantinople was known: why bother learning dozens of languages, acquiring different skills to handle a wide array of sources, or struggling in the small hours to make sense of the world - when what people really want to know how cats choose between chicken and liver, or whether different kinds of purring means different things ? A bit of a low point, really.

Forget Istanbul's crucial role in the new world order; forget the riots; forget Turkey's border with Syria and the acute refugee crisis; what's newsworthy as far away as India is that Barack Obama loves the cats of Istanbul.

I went to Istanbul as Indiana Jones and came back as Charlton Heston in Planet of the Cats - puzzled, perplexed and with a growing sense of doom.

A bit of a low point. Until I found something that put the fizz back into step, and got dusting off my (metaphorical) leather jacket, (imaginary) felt hat and (real) bull-whip. For that, though, you'll have to wait a few months till the book I've been working on for several years is done.

In the meantime, I understand The World According to Bob is doing brisk business: more copies sold this week than books on China, Russia and the Middle East combined.

Cats 1 Humans 0. The Apes would be proud.

And so last night, after what felt like months (precisely 12 in fact), Downton returned to the screen. The twitter-sphere lit up with gasps, comments about who looked good in bowler hats and much friendly 'advice' for the show's writers about current and potential future plot lines.

Downton thrives because it achieves a near-perfect blend of fact and fiction - with real events setting a context for the ups, downs and sideways for the Earls of Grantham. The very first episode of the very first series set the tone, with news solemnly reported of the sinking of the Titanic.

While Downton has been a phenomenon, a smash hit on both sides of the Atlantic, it bears many similarities with medieval and ancient Greek literature: blockbuster epics where the blend of reality and a bit of artistic license made story-lines as explosive, dramatic and gripping as the Sunday night prime-time slot is today.

That is not surprising, as all were intended as Entertainment (with a capital E). In the Byzantine Empire there were even the equivalent of the commissioning editor, the svengali looking for a smash-hit that would liven up dinner and the weekends, and get people gossiping at the water cooler (OK, at the baths).

The Alexiad was written in the 12th Century, for example, after the Empress Eirene asked for a good, racy account of the below and above stairs plots in the palace that would have given Downton a run for its money. Ooh - the servants Borilos and Germanos were planning a take-over from behind the scenes in 1080; who'd have believed it ! She even turned to a new writer to keep it going after the first person she commissioned keeled over and died after working too hard (that, and falling ill while on military campaign).

It's easy to think that people were any more forgiving about the blurred lines between fact and fiction then than they are today: Downton is sheer fantasy, says one commentator, sucking lemons. Look at all the historical errors, roar others, their lists eagerly picked up by newspapers with column inches to fill.

And it's made worse by the fact that it's so hard to pick out all the in-jokes and little references - the cheeky asides to Plutarch and Horace that would have brought chuckles, nods and winks to readers of the Alexiad, and to those who had sections of the text read out as after-dinner Entertainment. Just like references to rogue financiers, credit crunches and wars gone wrong abroad to in Downton, the trick was to make it all seem surprisingly modern and relevant - but about 'the good old days' at the same time.

Eyebrows would have raised at the depiction of some characters as being too good to be true and of others taken down a couple of notches. The people who supported the conspiracy of a certain Nikephoros Diogenes in the 1090s were fools, an 'utterly gormless' lot, convinced they were watching a genius when they saw their man chuck a spear a few feet through the air (Prime Time Saturday night audience watching Ant & Dec, perhaps). The hero of the Alexiad, by contrast, was scrupulously fair, always weighing the evidence carefully when given a choice, and really taking his time before making a considered decision (no idea how long it took him to choose from a menu, but you get the sense he was not the ideal person to grab a quick bite to eat with).

The point of the literature was to amuse and instruct, to give an insight into the past; it was certainly not to give a fact based account of history, reported in tones reminiscent of 19th century newspapers that would send you to sleep and question whether improving national literary levels were really worth the trouble. On the contrary - the more skullduggery, evil villains and heroic acts of selflessness the better.

Take Digenis Akrites, for example, one of the great poems of the medieval world (tragically understudied) and its tales of doomed love, of triumph over adversity, of daring and cliff-hangers that would make Julian Fellowes green with envy. Now THAT's Entertainment. Killing bears with your hands - take that Matthew Crawley (sniff); what's that - a dragon? Boom - gone! Think you can do better, Carson?

Or Homer, with the twisting plot lines, carefully-weaved story that was too neat and predictable for some. Well, of COURSE, Odysseus was going to make it home; what did you expect ??! Would his beloved old dog recognise him after only 20 years away; this is showbusiness, guys, so you do the maths. That Cyclops - did you really think he'd snaffle the hero ? Was that nice Branson going to - oh wait, that's Downton again.

The point is that Entertainment is, well, Entertainment. After my bit to push X-Factor viewing figures clearly worked last week, I'm hoping to have the same effect on Downton Abbey. Julian Fellowes, Anna Komnene and Homer; Lady Mary, Alexios Komnenos and Odysseus. 3,000 years of prime time all linked neatly together. You read it here first, people.

As far as our household is concerned, there are three New Years. One on 1st January (fair enough); another when school goes back in September (yes, OK); and another when the new season of X Factor starts at the end of August.

Thousands upon thousands of hopefuls queue up, drawn by the dreams of making in big and by the drive deep within the heart that makes almost every single one of them assert (usually through tears) that 'I really, really want this more than anything, I really really want it.'

I don't know how many other medieval historians watch X Factor - though a straw poll amongst my peers in Oxford suggests more than you might think (just because you obsess about William of Malmesbury's sources or about new coin finds by the Danube does not mean you're not human, you know!). It should be compulsory watching for anyone interested in the Crusades.

In 1095, Pope Urban gave an electrifying speech at Clermont in Central France, calling for armed men to join an expedition to save the Byzantine Empire which was teetering on the point of collapse (I have written a book about this). As word spread around Europe that something was going to be done to save Constantinople, the most important city in Europe with treasuries filled with Christianity's crown jewels, and better still, then carry on to Jerusalem, young men - and women - clamoured to take part.

Their motivations for doing so were varied, many of them conflicting: it was well-known that the journey east was long, dangerous and expensive. So leaving family behind was a wrench; and it cost a lot; and there was a good chance of not making it back alive.

But think of the rewards in the next life - that was the priests' favourite line. Sure. But also think of the glory, said the vaguer, medieval public school types; think of the financial rewards, thought the sharper ones on the make; think of what fun it will be, friends will have cajoled each other; think of what people will say if you don't go (a few of the sterner fathers would have tried that); and remember, darling, with thousands taking part, it will never be safer (the common sense of the mother, I suspect).

Unscrambling those is not easy, despite the solemn and dry explanations set out most historians of this period, who talk religious conviction, faith and endless variations of similar noble causes. Where's the fun, guys - and where's real life?

What about the peer pressure; where's the one drink too many, of course I'm coming promise that turns into something serious. Where's the showing off to the foxy daughter of the local landowner who's bound to be impressed? Where's the reluctant knight who had other things he was planning to do; or the one whose eyesight just wasn't that great and who didn't fancy it?

They are drawn, just like the Crusaders, by the conviction that the upside outweighs the downside: the shot at glory, riches, fame, eternal life made the risk of embarrassment, humiliation and (social) death worth it. Some are egged on by friends whose blind faith in their talent is touching - especially when it is profoundly misplaced; others are driven by desperation, by their fears and their hope of a better life.

For those who go on to the live shows - woohoo ! - and reach the final stages attain a level of fame claimed by those who returned from the Holy Land after the capture of Jerusalem in 1099. The Crusaders were feted and mobbed as One Direction are today; there were signings, portraits, songs - you name it - when they got home.

The Gary Barlow of the age was Bohemond: men wanted to hang out with him; women wanted to marry him. (I can tell you now, by the way, that our Gary is nothing like that 'Norman dog' as one Byzantine source called him).

Just like X Factor has its share of idiots, so did the Crusade. In the case of the TV show, the worst that happens is that security gets called and a can or two gets kicked by the wannabe hero who comes off the hinges; in the Crusade, there was no such safety net: thousands of Jews were murdered as the lunatic fringe went on the rampage, shouting ever louder how much they want it more than anything. The Y generation in the 11th century gave as little reason to proud as their peers ten centuries later.

This week David Attenborough has spoken of his belief that humans have stopped evolving. I can't tell you much about that. But what I can say is that human beings have not changed so much as some of my medieval historian colleagues think. Just because it was the Middle Ages, not all men were noble, not everyone was convinced by devotion, not all were pious, and not everyone was guided and led by their faith.

That, of course, is what the Simon Cowells of the day wanted you to believe. The medieval monks who wrote the histories of the Crusade and of this period were PR men par excellence. No superyachts, fast cars and messy relationships for them (erm...); but just like with the evil genius behind X Factor, the cash flowed in. All those cathedrals where you went if you wanted to hear real singing weren't free, you know.

The Four Lads may not feature on many bibliographies on the history of the great imperial city of Constantinople. But they were spot on.

'Istanbul was Constantinople', they sang, entirely accurately. 'Now it's Istanbul, not Constantinople'; correct again.

'Why did Constantinople get the works?' they mused; 'That's nobody's business but the Turks'

It's a classic - an all time great, and required listening (you can click on the link above and listen as you read if you like).

Despite the wisdom of the Four Lads, though, some things never change. The inhabitants of the great city nestled on the banks of the Bosphorus have been up in arms, protesting against the heavy-handed and bloody-mindedness of the Prime Minister, Recep Tayyip Erdoğan. It is the latest in a long and proud line of civic disobedience that stretches back to the early 4th century when the city was magnificently endowed by the Emperor Constantine.

As Byzantine Emperors and Turkish sultans learned from experience, when crowds take to the streets of the city, it was time to listen. Erdoğan is not interested; it's all the fault of 'provocateurs' and 'social media', he claims. He should study his history.

If he had, he'd quickly learn about the Stylites of Constantinople, men who would climb to the top of a column to be closer to God, and to demonstrate their devotion through their asceticism. Some, like Daniel in the 5th century, took up position by the harbour, so those journeying in and out of the city could see him literally standing up for what he believed in. People would shout up questions to him - and he'd answer, impressing all with his simple advice.

For all those who say history does not repeat itself, how wonderful to see that after being swamped with tear gas, the protesters in Istanbul have reverted to old tradition of making a stand.

The symbol of the recent protests is none other than a modern day stylite - dubbed the standing man.

He stands still, silently (occasionally disappearing to change his outfit); his aim is to make a pacific and ascetic protest against the powers that be. He will hold his ground, and do so proudly, quietly and without a fuss. The stylites of old would be proud of him - and delighted to see their traditions being re-adopted, even if the spiritual side is rather watered down.

Even better, clusters of new standing figures have now joined him. This happened too with popular stylites in the old days, with others setting up columns near by (I might be wrong, but suspect this was really annoying for the first holy man who got in to position; I bet there was a lot of the silent treatment for new arrivals until they proved themselves). And despite what they say, size did matter - what was worse than another stylite joining the party? A stylite with a bigger column, that's what.