Very nice.
At the Anarcho-Syndicalist May Day in Stockholm today, which often is drastically larger than that of the mainstream "Left Party" and/or the (formerly leftish) "Social Democrat" party's, there was another flag this year,
that of the Combat Organization of Anarcho-Communists ("BO AK", http://boakor7dmr63zguccltp6nki56ou4oppirhyllfck7yd3sifywinhkyd.onion/index.php/en/) in Russia, resisting Putin's imperialist war in Ukraine through for example derailing trains, destroying conscription centers and other marvelously excellent actions.
The building it's hanging from would seem to be the old Stockholm stock market building, in front of which the anarchists, syndicalists, antifascists, etc hold their speeches and sing revolutionary hymns every May Day.