Who discovered Stockholm?

The city of Stockholm was likely founded in the 12th century by Birger Jarl, the founder of the House of Bjelbo and the first sovereign ruler of Sweden. According to tradition, Birger Jarl built his castle at the mouth of Lake Mälaren, at a place called "Stockhome" (literally, "home on the pile"). The name Stockholm is first mentioned in a document from 1252.