▁A ▁modern ▁story ▁dated ▁back ▁to ▁the ▁mid ▁ 1 7 th ▁century , ▁tells ▁how ▁the ▁population ▁of ▁Bir ka , ▁a ▁historical ▁city ▁on ▁Lake ▁M ä lar en , ▁grew ▁too ▁rapidly , ▁and ▁the ▁God s ▁then ▁consult ed ▁ur ged ▁parts ▁of ▁the ▁population ▁to ▁em igr ate ▁to ▁a ▁new ▁site . ▁To ▁determine ▁where ▁to ▁build ▁the ▁new ▁city , ▁it ▁was ▁decided ▁a ▁log ▁bound ▁with ▁gold ▁should ▁point ▁out ▁where ▁to ▁sett le ▁by ▁sail ing ▁ash ore ▁on ▁the ▁site , ▁and , ▁occasionally , ▁it ▁land ed ▁on ▁an ▁is let ▁in ▁what ▁is ▁today ▁central ▁Stockholm . ▁ ▁According ▁to ▁a ▁ 1 7 th - century ▁myth , ▁the ▁tower ▁Bir ger ▁Jar ls ▁torn , ▁often ▁and ▁err one ously ▁said ▁to ▁be ▁the ▁oldest ▁building ▁in ▁Stockholm , ▁was ▁built ▁on ▁this ▁location . ▁ ▁Origin ▁ ▁According ▁to ▁the ▁Chron icle ▁of ▁Eric , ▁written ▁in ▁the ▁ 1 3 2 0 s , ▁Stockholm ▁was ▁founded ▁by ▁Bir ger ▁Jar l ▁around ▁ 1 2 5 0 ▁as ▁a ▁lock ▁to ▁the ▁Lake ▁M ä lar en ▁region ▁( la as ▁fore ▁then ▁s io , ▁" lock ▁before ▁that ▁lake ") ▁in ▁order ▁to ▁prevent ▁pir ates ▁from ▁reaching ▁the ▁seven ▁cities ▁and ▁nin ete en ▁par ishes ▁around ▁it . ▁ ▁Another ▁medieval ▁source ▁( Vis by ann al erna ), ▁however , ▁claims ▁the ▁city ▁was ▁founded ▁in ▁ 1 1 8 7