When Keith Waterhouse’s fictional fantasist Billy Liar wanted to escape from the horrors of the real world, he would retreat to a place inside his head called Ambrosia. The Situationists, meanwhile, charted psychogeographic maps of European cities, navigating places by mood rather than geography. There is much of the spirit of both in Jerry Gretzinger’s ever-expanding map of an imaginary world, which the American artist has been painting for more than 50 years, and which currently numbers some 3011 sheets of A4 paper.

‘It goes way back to my childhood,’ 79-year-old Gretzinger explains on the eve of his parallel universe’s first appearance outside the US. ‘I was fascinated with maps, and would imagine these places, because we didn’t travel much. Then at some point I started making my own. That grew out of playing with my brother on this little plot of land we lived on. We created this little model village out of dirt, and then I started translating that on to paper. For me it’s a form of escapism, I guess.’

Gretzinger will update his increasingly multi-dimensional map while in Edinburgh and beyond. ‘It frustrates me,’ he says, ‘because there are a couple of new dimensions I want to bring in, but they take time, and although I probably won’t be around to finish them, I want to keep doing it as long as I can.’

Summerhall, Edinburgh, Sat 7 Dec–Fri 24 Jan.