When he developed his Theory of Relativity, Albert Einstein was living in what capital city?

It was not in a prestigious university laboratory, but in a modest apartment in the Swiss capital that modern physics was fundamentally reshaped. From 1902 to 1909, Albert Einstein worked as a technical expert at the Swiss Patent Office in Berne. This seemingly mundane job gave him a steady income and, crucially, the spare time to ponder the nature of space, time, and light. It was here, in this quiet European city, that he developed the core ideas for his Special Theory of Relativity.

The year 1905 is now celebrated as Einstein's "annus mirabilis," or miracle year. While living in his Berne flat, he published four revolutionary papers that changed the course of science. In addition to the paper that introduced special relativity, he also published works that explained the photoelectric effect (which would later win him the Nobel Prize), proved the existence of atoms through the study of Brownian motion, and introduced the world's most famous equation, E=mc².

This period in Berne was arguably the most creative and productive of his entire life. The city provided the stable environment where his thought experiments could flourish, transforming him from an unknown patent clerk into the world's most renowned scientist. His former apartment at Kramgasse 49 is now a popular museum, preserving the humble setting of these extraordinary scientific breakthroughs.