Detail from Gordon Cullen mural at Greenside Primary School, London W12

Detail from Gordon Cullen mural at Greenside Primary School, London W12

The third weekend of September is always the best time of year to be in London. On 21 and 22 September, the annual Open House London event will see the city throw open its doors to anyone with an interest in architecture. For the price of an Oyster card and a few fortifying cups of coffee you can enjoy this celebration of London’s buildings in all their diversity.

Despite what you may have read in the “posh” papers, Open House London isn’t just for architecture snobs or fans of TV property porn (“Double your home and piss off the neighbours”). Veteran broadcaster Joan Bakewell writes of her enthusiasm for this event, which has been running since 1992, but then ruins it all with the fateful words “It attracts the kind of people who watch Channel 4’s Grand Designs”. God, I hope that’s not true.

I loathe C4’s Grand Designs and its smarmy presenter, Kevin McCloud. No doubt some of these home-owners do have unimpeachable taste, vision and a genuine desire to enrich their neighbourhood with great architecture. But against that you have to weigh the weekly parade of rampant egomania, selfishness and lack of fiscal responsibility that characterises many of these schemes. You wouldn’t want to live next door to any of these people, would you?

While high-profile developments like the Shard and Battersea Power always grab the headlines and draw the crowds, they’re not what makes Open House special for me. I’ve been going since 2007 and, as Joan Bakewell also points out, much of the fun lies in discovering what is just around the corner from you.

So while the Grand Designs groupies are queuing to see the next wave of penthouses for philistine Russian oligarchs, I’ll probably be closer to home checking out an architectural curio like Greenside Primary School in W12. It was designed by Erno Goldfinger (he of Trellick Tower fame), and features a colourful mural by Gordon Cullen. More important, my good friend Jo spent her formative years at this school.

Sadly Greenside was the only building I saw last year, in a weekend that started brightly and turned (literally) into a washout. But if you’re well organised and not deterred by bad weather or unreliable public transport, it’s amazing what you can see in London in just a few hours – without getting sucked into expensive tourist traps.

Two years ago I wrote about my visit to Kensington’s Commonwealth Institute, which was about to begin its transformation from a dilapidated 1960s icon to the shiny new home for the Design Museum. On the same day, I also enjoyed the panoramic views and quasi-Mediterranean atmosphere of the Roof Gardens above Kensington High Street.

The Roof Gardens, Kensington, London W8

Then it was on to the Leighton House Museum, the home and studio of Victorian artist Frederic, Lord Leighton. Here, as the website enthusiastically proclaims, “East meets West” in the form of the extravagantly designed Arab Hall with its massive chandelier, mosaics, rugs and indoor fountain.

From Victorian eclecticism at its finest, we moved on to the Peter Jones store at Sloane Square, which is better known in my family as the place where Charlie (aged six) buys his LEGO. This branch of John Lewis is used to coping with enthusiastic crowds of Prada-toting bargain hunters elbowing their way through the Kitchen department. On this occasion, though, we’d all come to admire the glass curtain wall of this William Crabtree-designed 1930s building.

This year I’ll be volunteering at the William Morris Society in Hammersmith on Saturday, before heading south of river on Sunday. The Glasshouse, a Terry Farrell-designed residence in Petersham, was on my list last year, but now I’m leaning towards something a bit older, though equally eye-catching in its own way.

I visited Horace Walpole’s newly renovated gothic castle Strawberry Hill House on my birthday a couple of years ago. Though the gardens were still a work in progress and it was a dull November day, the house was magical. So even if it’s not sunny on Sunday, I think a return trip to Strawberry Hill will make Open House London 2013 a vintage year.

Strawberry_Hill_House_May_2013_22 (pic Jonathan Cardy)