Daughter C and I had decided a day off was in order. Which presented two problems for me: one is that a day off not seeing what there is to see in Innsbruck seemed to be transgressing some law of tourism, and two, what would I blog about? I needn't have worried.

Early afternoon I decided to explore some of the old part of town, the one with the charming ornate buildings, narrow streets, bell towers, churches and hidden treasures only discovered by nosing around.

As I got closer I found I was following two witches with matching broomsticks, then a couple of pink rabbits holding hands. People wearing glittery hats and Venice carnival-style masks hoved into view too; I realised something was up.

And it was. As I finally got into the old centre I could see people were heading in one particular direction - more masks and costumes - and finally, that sure sign that something organised is going on: security personnel in hi-vis jackets and FBI earpieces. The polizei were obvious too. Rucksacks and large bags were being searched at pinch-points.

The thump of music reached my ears - had I been dressed as a rabbit they would have twitched. - and finally I found myself in a throng of all ages, dressed in all manner of costumes and masks. A stage with DJ was pumping out dance beats, a crowd of families, teens, old blokes (I was relieved), and three hens with saxophones confirmed without a doubt that This Was It.

There were beer and food tents I saw Spiderman smoking - he had cut a neat hole in his face mask in order to puff on the cigarette. William Tell bumped into me, and I saw Homer Simpson in 3D. Two women riding geese paraded through the crowd, and a coven of purple and black witches surrounded a busker for a photograph. He was never seen again.

Those who hadn't gone to the extremes of costume had faces painted, or wore antlers - as yo do. I just wore a smile, and clicked away with my camera.

The crowd was thickest in front of the DJ's stage, mainly younger people dressed in animal onesies, with faces painted in whiskers or lion mouths. They were dancing like there was no tomorrow. I asked a shop assistant what it was all about but she just shrugged and said, 'No particular reason,' which I found hard to believe.

I can't imagine the burghers at their last gathering all agreed, 'Ja, ve must have ein carnival, for nein particular reason. Break open ze taxpayer coffers!'

My Innsbruck free wifi connection also insisted on keeping the event secret, but I suspected it must have been something to do with being the last day of February, of winter, and Shrove Tuesday.

I was right. When I finally did get internet access, on Ash Wednesday, I learned that there was a carnival period from St. Blasius until Shrove Tuesday, with ancient Shrovetide rituals kept very much alive in Innsbruck and its holiday villages.

No doubt such celebrations have morphed from their original religious origins and now provide an excuse for a party. I was thinking of asking Zorro to confirm this for me, but he disappeared into the crowd followed by Harry Potter. A family of three native Alaskans strolled by, so I didn't have to guess any more. I knew it.

I met up with Catherine in a side street in Innsbruck's smallest bar, aptly named Nano Bar, where we compared notes. About six metes square, you could fit sixteen people in cozily, maybe 20 if they were used to taking saunas together, while a couple more tables and leaning-ledges outside the front door coped with any overflow.

A tiger walked in, accompanied by his trainer who was wearing patchwork-quilt overalls. And then, silence fell across the room (it didn't have far to go) as the door opened again and all eyes turned, to Elvis.

Yes, the King of the Carnival had arrived, complete with flashing glasses.

Thank you very much.