For the comic book series issue of the same name, see Moscow (issue).
Moscow is the capital of Russia. Queen Consolidated has an important subsidiary there, and it was the birthplace of Isabel Rochev. Among its current residents (and presumably one of the city's fabled plethora of billionaires) is Anatoly Knyazev, leader of the Solntsevskaya Bratva and personal friend of Oliver Queen.
Oliver Queen, John Diggle and Felicity Smoak, along with the last minute addition of Isabel Rochev, traveled to Moscow, ostensibly to check up on the Queen Consolidated holdings and attempt to shore up the company's flagging stock profile. In truth, Dig was looking to locate and rescue Lyla Michaels, who disappeared there while tracking down Floyd Lawton for him. To do this, he got himself arrested, and Oliver sought the help of his old friend Anatoly Knyazev, to purchase the drugs that would get Dig consigned to the hell-hole he believed held Lyla. Oliver revealed his fluent Russian to Isabel, and the two ended up in bed together, although only very briefly, as Isabel was not a "cuddler". They both appeared to take a "what happens in Russia" line, however Felicity was rather less forgiving of Oliver's lapse in judgment.