We're always being told that there isn't a British provincial repertory theatre system in the way there once was, since the allegedly glorious old reps were decimated in the funding cuts of the Thatcher years. No, we're not bringing forth a generation of seasoned thesps of the likes of Julie Walters or Bill Nighy or Sir Ian McKellen or all of that great breed of character actors which emerged from the world of seedy dressing rooms and dodgy digs back in the days when there were only two channels on the television for a few hours a day. But if that's true, how come they seem to be building theatres like mad right now?

The world of the old reps never died - it thrives again in such places as Liverpool and Birmingham, Stoke and Dundee, Plymouth and Nottingham. The ultimate reps are still the National Theatre in London and the Royal Shakespeare Company (RSC) in Stratford-on-Avon. But the general public might be forgiven for not caring very much about a system that emerged in the early 20th century as a (generally subsidised) way of bringing culture to the masses. So what that a rep is effectively a theatrical factory - a producing theatre with a regularly changing programme, usually staged by resident companies of actors? How is anyone to know that a building generates theatre rather than merely being - in the jargon of the trade - a "receiving house"? Surely all that matters is that your local theatre is running a good show, and who cares where it comes from? Besides, what of that older tradition of the strolling players - the troupes of actors who have no fixed abode?

This, I think, is a London-centric attitude. Some provincial towns and cities can still boast that enviable thing, a loyal customer base for their theatres. So we find that the Belgrade Theatre in Coventry - where the young Ian McKellen first took to the stage in 1961 - has just been much extended and rebuilt with a second £11m auditorium by architects Stanton Williams, who spruced up the National a few years back We find that the old Leicester Haymarket is being reborn next year as a brand-new, 1,000-seat, £50m radical glass-spaceship of a building by New York-based architect Rafael Vinoly. That the Crucible in Sheffield is starting a two-year, £15m revamp. That the famous Hull Truck theatre, the urban-edge domain of John Godber of Bouncers fame, is building a complete new £10m home for itself by architects Wright and Wright. That the RSC, having scored a big success with its temporary courtyard theatre by Ian Ritchie, is now spending £70m or so on rebuilding its main auditorium to designs by Bennetts Associates. Nobody seems to have told the theatre world to stop building once the Lottery-boom years were over. Partly because there are still all kinds of regional and European grants going.

So it seems to be something of a golden age for theatres, if not necessarily for theatre as an art form. Some of these examples are modest, some undeniably spectacular, by top names. Me, I particularly like one you can hardly see at all, by architects you've never heard of. This is Live Theatre, in Newcastle.

Live Theatre is the exact opposite of the glittering peanut of the Sage concert hall by Norman Foster across the Tyne. It's a working man's club kind of place, created by socialists back in the days when there were still a few miners and shipyard workers in the area. It found itself a home in some historic but decaying buildings down behind the quayside. And slowly, it became a centre for new writing, a sort of Royal Court of the North-East. Lee Hall, the man who wrote the script that became Billy Elliot, did it here. It's Hall's new play, The Pitmen Painters, which recently re-opened the place after a £5.4m extension.

The new Live Theatre is not high architecture - originally it was hardly designed at all, just converted, a bit here, a bit there, as funds allowed. Now it has a bit of a designerly look to it, but it's not wussy, mind. It knows exactly what it has to do. The tiny auditorium - wrapped eccentrically round one corner of its old warehouse, with the square stage occupying the opposite corner - is as a result a miniaturised version of the National's Olivier, which adopts much the same geometry. This is probably a complete coincidence. A new steel and glass stairtower brings daylight down to a new foyer and bar. Of course, you can take your pint into the play - the punters wouldn't come if you couldn't. There's a second auditorium perched up in the roofspace, rooms for writers to agonise in, a new Italian restaurant in an old ship's chandler's at the front - it's all completely unpretentious and it feels exactly right. The architect is Aidan Jackson of the local firm Waring and Netts.

The whole thing has a kind of shipyard toughness to it. You don't get that London obsessing about the elegant detail. What Live Theatre feels like is what its name implies: it's the productions that count, not whether the place wins design awards or not. Well, I'm sorry, but it should.

Here's an interesting thing. I bet you didn't know that Newcastle/Gateshead has more active theatres per head of population than anywhere else in the UK. I certainly didn't. From the gritty Northern Stage to the gracious Theatre Royal, the Geordies can't get enough of it. And with audiences like that, you just can't say that provincial rep is dead. It looks pretty healthy to me.