It may be your local pub or park, your gym, or your closest cafe. A particular public bench where you go to read or think, or your neighbourhood library.

The “third place” is a public, social place where you spend time that is neither home nor work. Whether it is publicly run, like a library, or a commercial venture, it is, above all, shared – a site of community-building and interaction with others.

The concept was brought to the fore by the US sociologist Ray Oldenburg in his 1989 book The Great Good Place, in which he explored the positive contribution of the third place to democracy, neighbourhood communities and residents’ wellbeing.

It was just this sort of organic interaction that Eugene Quinn was attempting to replicate with his monthly Coffeehouse Conversations meet-up in Vienna. “If you wander into a pub in Dublin or a diner in America, you’ll be able to meet locals quite quickly – in a coffeehouse in Vienna, not so much,” he said. “People don’t drift into each other’s worlds.”

But increasingly, we have fewer options.

John Harris has decried the loss of shared spaces in Britain, pointing to the decline of religious affiliation, closure of pubs and music venues, and cuts to public services as “leaving us a nation of cliques”. With city-dwellers in particular operating within silos, Harris writes, “maintaining community life is an ongoing struggle”.

Last week findings showed that London parks – ostensibly public spaces – were more off-limits than ever before as councils rented them out to host music festivals. Alex Clark wrote about the implications:

Nobody can say what a park means to all its users. Nobody knows what conversations are provoked as we stroll along, what agonies soothed or problems thought through. ... These dwindling spaces are precious and should be protected from commodification and the modern disease of constant, organised fun.

Now we want to hear from you.

Share your experiences

Where is your third place, or favourite, most often frequented shared space? Where do you find yourself falling into conversation with strangers and having – as Harris writes – “the best kind of chaotic, unexpected experiences”? Will you tell us about one?

Plus: have you noticed the loss of shared spaces in your home, and does it concern you? How would the closure of your third place affect your life?

Please share your experiences with us using the form below – or, if you’d prefer to speak with a member of the team directly, you’re welcome to email Guardian Cities communities editor Elle Hunt via elle.hunt@theguardian.com.

We will publish a series of responses in the coming weeks.

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