Short answers, pulled from the story.
Berthold V, Duke of Zähringen, established the fortified settlement on the Aare river peninsula in 1191. This site became the medieval city proper after earlier Celtic and Roman settlements existed nearby.
Deputies chose Bern as the Federal City seat for the newly created Swiss federal state on the 28th of November 1848. The constitution does not define Bern as an official capital but designates it as the government seat.
The Old Town became a UNESCO World Heritage Site in 1983 because it retains its largely medieval structure. The site sits on a hilly peninsula surrounded by the river Aare with unique topographical challenges.
Live bears have been kept in the Bärengraben since the 1440s according to earliest references. Four current bears occupy an open-air enclosure while two young bears received as gifts from Russia stay at Dählhölzli zoo.
Holy Roman Emperor Frederick II granted Bern free imperial city status by 1218 through the Goldene Handfeste document. The city joined the Swiss Confederacy in 1353 as its eighth canton during the formative period spanning 1353 to 1481.