Midnattsloppet (Swedish for "The Midnight Run") is a running competition organised in Stockholm, Gothenburg and Malmö in Sweden, as well as Helsinki in Finland, by Midnattsloppet Nordic AB, a daughter company of Hammarby IF. Stockholm. The first Midnattsloppet run was held in Södermalm in Stockholm in 1982 and has been held annually since. The length of the run varied until 1995, when it was set at 10 kilometres. In recent years, the run has been controlled by officially licensed referees. The run is held on a Saturday in the beginning of August every year.
https://en.wikipedia.org/wiki/Midnattsloppet