I am in love. She's Norwegian, gorgeous, full of fun, yet with surprising hidden depths. Quite literally so, since her lower limbs are permanently submerged in the sea. No, she's not a mermaid. She's the new Oslo Opera House, an amazing marble and granite vision that rises out of the fjord like a giant ice floe.

Her opening night, last Saturday, was the must-have opera ticket of the year. I was there. So, more importantly, were the assorted royal whatnots of Norway, Sweden and Denmark, plus the Norwegian Prime Minister, the President of Iceland, and Angela Merkel, the German Chancellor. Sadly, nobody came from the British Cabinet or Royal Family, despite a huge input into the project from a British company, Theatre Projects. No surprise there, though. After all, this was a celebration of culture. You wouldn't expect the British Establishment to get excited by that.

And culture came by the bucketload. The opening gala started at 6.30pm with some unusual foyer music: four percussionists playing tunes (let's be charitable) on some of the 36,000 marble slabs used in the building. And it ended - 30 arias, five ballets and nearly six hours later - two minutes after midnight. After which, audience and performers caroused till the sun came up.

And after that I climbed on to the roof - because one unique aspect of this building (designed by the architects Snøhetta) is that, on either side of the foyer, the huge roof comes tapering down like giant ski slopes. And because the opera-house authorities are unencumbered by nannying EU health-and-safety legislation (the Norwegians, you will recall, have stood aloof from all that malarky), they have decided to allow the public to clamber up these granite slopes to the very top of the building, where there are fine views of the fjord and city.

The democratic symbolism of that gesture is itself symbolic of the way in which the public has been involved in this project from the start. And that's why I'm so keen to tell you about it. It makes such a refreshing contrast to the way that major building projects are mishandled here.

Admittedly the Norwegians spent the best part of a century pondering how best to provide a home for their national opera and ballet companies. But when the decision to build was finally made, in 1999, there was no messing around. The Government undertook to foot the entire £350 million bill - no buck-passing Public Private Partnerships here! And the public was invited to view all 350 entries in the competition to select the architect. Some 70,000 Norwegians did so, and their opinions - on the look and function of the theatre, and its role in national life - played a large part in the planning.

That vital democratic imput was evident even at Saturday's gala. Halfway through, a vast choir - more than 450 strong - advanced down the stage, kitted out in everything from Norwegian national dress to hard hats, and delivered one of the most spine-tingling performances of Verdi's Chorus of the Hebrew Slaves that I ever expect to hear. But these weren't profess-ional singers. Every district in Norway supplied one ordinary citizen to make up that enormous choral army. “I'm sorry about that item; it was pure politics,” an official said to me later. But I felt that no apology was needed. Quite the opposite. If ever a performance proclaimed “we, the people, own this theatre”, this was it.

I could rave on and on about other aspects of the building. The acoustics of the main auditorium (there are three in all) are stunning: a luxurious 1.9-second reverberation, unprecedented in an opera house. And when you step into the theatre's heart - in contrast to all the dazzling marble outside - you are suddenly plunged into a world of oak, stained in a multitude of rich hues. It's as if a majestic tree has been embedded deep inside a glacier.

Then there's the way that the work of top painters and sculptors has been integrated into the fabric, rather than being tacked on as an “arty” afterthought, as so often in Britain. Even the loos are an artwork. You walk into what looks like a shimmering metal grille (designed by Olafur Eliasson, the Icelandic artist who put that giant sun into Tate Modern a few years ago), and find yourself not in a gents' lavatory but in a piece of visual theatre, where the urinals glint with concealed lights and the cubicles are a riot of mosaic. Gobsmacked, I lingered so long that I was in danger of getting myself arrested for loitering with intent.

And finally there's the sheer boldness of the original decision - to plonk an opera house half submerged in a fjord. How strange for musicians in the pit, to know that they are sitting 40ft below the level of the sea, just the other side of the wall. It really does feel as though the building, like Norway's mountains, has been thrust out of the waves by some primordial catacylsm. Very operatic! Wagner would have loved it.

Such audacity created some formidable technical problems - and these, too, have been triumphantly solved. This must be the only theatre in the world with its own underwater sea defence: a huge barrier, 6ft below the waves. Its function? Not to keep the sea out, but to protect the theatre from the Oslo-Copenhagen car ferry, should it ever drift off course in bad weather. The Norwegians have thought of everything.

Yes, I could rave about all that. But what most struck me was the pride that ordinary Norwegians clearly take in their new opera house. How is that possible, when so many cultural or sporting mega-projects in Britain, from Wembley and the Wales Millenn-ium Centre to the Dome and the Olympics, end up mired in controversy and loathing? Are the British simply more cynical than the Norwegians? Or is the British track record of delivering prestigious projects on time and budget so chequered that British people have lost all appetite for building them?

That's something for you to ponder. Me? I'm too busy checking out budget flights back to Oslo, and the new love of my life.

On the seventh day, thou shalt be duped

One dubious thrill of returning to Terminal 5 on a Sunday is that you discover that there's an even sleazier racket being inflicted on the travelling public than the Heathrow Express. Yes, it's the Heathrow Express Sunday service! A sign says “train every 15 minutes”, so you grudgingly fork out a whopping £15.50 for the 15-mile journey. You then get down to platform level and discover that the next train departs in 26 minutes' time. Some express service! You'd have been halfway to Central London on the Tube, had you known the full facts. “But it's Sunday,” says a station assistant when you confront her - as though her company has a special licence to con the public on the Day of Rest.

Incensed, you go all the way back up to the ticket office to demand a refund - only to find that the queue is so long that you use up the 26 minutes waiting to reach the counter.

Welcome back to rip-off Britain.

Housing market forces

Did you utter a mean-spirited cheer at the news that 4,000 estate agents may be forced out of business this year? Did you even mutter that, in some respects, the recession has much to commend it. I did. But immediately I felt a pang of guilt. This glee about estate agents falling on hard times is hypocritical, isn't it? After all, we're all happy when they fib on our behalf. It's rare to hear of a seller refusing to accept an inflated offer for his house because he thinks his estate agent may have overstated its merits.

No, the least we can do, at this time of existential trauma in agentland, is to think of alternative jobs for those cast out of the property world. Where would their talent for gilding the lily of truth be most usefully applied? In BA's customer services? Presenting the budget for the London Olympics? There's a bottle of bubbly, in a much sought-after location (under my desk), for the best suggestion.

Times Recommends

• The ghost of Robin Cook haunts Chilcot’s feast
• The truth shouldn’t need oaths
• Violence: let’s separate the men from the boys