In the summer of 1992, the literary and journalistic magazine Yunost published a novel by the author and screenwriter Vladimir Gonik entitled Preispodniaia (English: Abyss), set in an underground bunker in Moscow. Earlier, in the spring of that year, excerpts from the novel had been published in the weekly newspaper Sovershenno sekretno (ru). In an interview with both the newspaper's editor and Gonik in 1993, the author stated that the term "Metro-2" had been introduced to them, and that the novel had been written based on information collected over the previous 20 years by the two of them on things such as secret bunkers and the underground railways connecting them. Gonik admitted that he had worked on the book between 1973 and 1986, and that some of the more sensitive information had been purposefully misrepresented.
In later years, Gonik has argued that the bunkers, and therefore the so-called "Metro-2", had been for use by the leadership of the Politburo and the Communist Party of the Soviet Union (CPSU), along with their families, in case of war. According to him, in the early 1970s the General Secretary of the CPSU, Leonid Brezhnev, personally visited the main bunker, and, in 1974, awarded the Chairman of the KGB at the time, Yuri Andropov, the Gold Star Medal of the Hero of Socialist Labour. Apparently, each member of the Central Committee had a 180m2 apartment, with a study, lounge, kitchen and bathroom. Gonik claims to have gathered this information working as a doctor in the polyclinic of the Ministry of Defence.
After the publication of the novel in 1992/1993, the subject of a second, secret, underground railway has been raised many times, especially in the Russian media. In particular, the magazine Ogoniok has referred to a "Metro-2" several times.
Source: Wikipedia