Before I did the tour, Russia made no sense. It's such a dense, confusing place. Nothing you think will happen there ever does.
The problem, a friend of mine reckons, is that you expect Russia to be European but it's not. It's its own entity, its own continent. The rules are completely different.
And I'd arrived in St Petersburg clueless. The language is different, obviously, but so is the alphabet. Guidebooks and maps are printed in English, which is great for reading them but no so great for translating whatever is on the page to whatever it is you're seeking around you.
With signage in Cyrillic, a bar becomes what looks like a "bap". A restaurant becomes a "pectopah". Severe embarrassment ensues when you try to pronounce these words the way you see them, thinking that's the Russian translation. Inquiries about pectopahs are met with stony silence. (Only later does it become clear that almost everything is met with stony silence.)
Finding your way around is a nightmare. Map references are in the Roman alphabet - Russian street signs are not. This results in days of wrong turns and desperate pleas for help with directions. And, of course, stony silences.
Russia is not a place of overt joy. Even its passions are dark and moody. Have you ever tried to actually read Dostoevsky? It ain't exactly Dr Seuss. It's bleak and troubling, much like the country that inspired it.
So many bizarre sights. Two men at a restaurant, deep in conversation, an ice bucket propped next to them holding a bottle of wine. Glasses empty, one of them pulls out the wine and begins pouring a couple of large shots.
Wait - shots? Of course, it's not wine; it's a bottle of vodka. The two polish the thing off before dessert has arrived.
I try a shot of my own, attempting to fit in, and almost choke. It's strong and harsh, there doesn't seem to be any joy in it at all. Again, much like its country of origin.
Even things that are the same are strangely different. Girls dress in Western clothes but not in any combination I've seen before.
A Monday morning on Nevsky Prospekt, St Petersburg's main street, and most of the women look like they're going to a fancy dress party that has the theme "street walker who got dressed in the dark". There are knee-high boots with leopard-print mini-skirts and leather jackets. Torn fishnet stockings and denim hotpants. And it's freezing out there.
An ice hockey game should be relatively familiar but even this has its quirks. Cheerleaders take to the ice before the game to perform a routine but when they're finished, they walk into the stands and sit in the stairwells with the crowd.
One takes a seat right near my partner and I. There's me, then my partner, then a stunning Russian cheerleader. Where to look?
None of this makes any sense. And there's no one to ask for an explanation. The problem is that the Russian facade is so hard to pierce. The usual tricks - a smile and a pathetic attempt at the local dialect - won't do the trick. They're met with more stony silence.
With no human touchstones, it's impossible to get a grip on the place. There's no sense of belonging, or understanding. You feel like you're floating on the surface looking in - and Russia is deep. You're like a snorkeller trying to peer into the Mariana Trench.
That's when I decide to do the tour. I'm not usually a city tour kind of guy - I cringe when I see those open-topped buses cruising by. I like to discover things for myself. But this is a special circumstance.
So I sign up for an "underground tour" with a guy called Petr. The idea is that he'll show me some of the lesser-known sights of St Petersburg: the illegal music venue where bands played during the Soviet era; the home of Kolya Vasin, a local so obsessed with the Beatles that his house has become a shrine; and a traditional old pub, or as I like to call them, a "bap".
But what Petr doesn't know is that his main job for the day will be helping me get a grip on his country by fielding inane questions. Such as, why do the girls dress like that? "For years," Petr says, "in communist times, we were told how to dress. Now you can wear anything you want - so we go a little crazy."
Why doesn't anyone return a smile? "The Russian people, they don't smile all the time. If you walk around smiling, they think you are crazy."
At the pub, Petr teaches me to drink vodka properly. "Always drink it with food," he says, necking a shot and then taking a mouthful of bread and cheese. He's right - it works.
There is, however, one problem even Petr can't help me understand.
"Pectopah?" he says, "I have never heard of this thing."