I arrive at the Szepilona Bisztro, on a leafy boulevard on the Buda side of Budapest, clutching a Rubik’s Cube and searching for the man who created it almost 50 years ago. I feel unworthy to have lunch with Erno Rubik, not least because the Cube I am holding has never been solved. When a waitress approaches, I proffer it, explaining that I am dining with its creator. An awed smile spreads across her face.

Rubik arrives punctually and without fanfare. The 76-year-old is healthily tanned, his manner by turns boyish and professorial. He’s been coming to this restaurant since the late 1960s, when he was a graduate student, before he invented one of the world’s most successful and brain-busting puzzles — a cube with 43 quintillion combinations, only one of which is correct.

His moment of inspiration came in the spring of 1974, when Rubik was living in his family’s apartment on a grand avenue on the Pest side of the city, which is separated from the hilly Buda side by the Danube. He was a professor of architecture, but his room was “l(fā)ike a child’s pocket, full of marbles and treasures”.