This map shows a neighborhood in Vienna, Austria, where many of the key political characters of the last century happened to live, work, and/or hang out. All of them were there in 1913, and many crossed paths in one way or another. The discussion at reddit tells us more.
Stalin was in Vienna for a month or so.Further confirmation is found in the history of Café Central, a popular meeting place for young intellectuals, including several from the map. While Vienna has long been a cultural Mecca, you have to wonder if there was anything odd added to the water supply in 1913. (via Strange Company)
Tito worked in a factory.
Trotsky lived there 1907-1914.