Bad apartment - apartment, in which the action of the novel by M. A. Bulgakov "The Master and Margarita " took place, including the "Ball of Satan". The address indicated in the novel is Moscow, Bolshaya Sadovaya, 302 bis, fifth floor, apt. No. 50
According to Boris Sokolov 's Bulgakov Encyclopedia, apartment No. 50 in house No. 10 in B. Sadovaya Street in Moscow , where Bulgakov lived in 1921-1924 , served as a possible prototype for the bad apartment. This apartment was a communal apartment of the corridor type and consisted of several rooms where different families lived. Some features of the layout are similar to apartment number 34 in this house, where the writer lived in August-November 1924 . According to the memoirs of Bulgakov’s first wife , a woman lived in apartment No. 50, who was the prototype of Annushka from the novel.
Apartment number 50 is also mentioned in other writer's works: “ No. 13. - The House of Elpit-Rabkommun ”, “Psalm”, “ Moonshine Lake ”, “Remembrance ...”.
In 2004 transferred to the Bulgakov Foundation  . Now there is a museum .
Two years before the start of the novel, five tenants mysteriously disappeared in a week from the “bad apartment” and the “correct policeman in white gloves”, who came to one of the tenants. Other tenants of the house for a long time told incredible legends about what happened, but after a week the director of the Theater Variety Stepan Lihodeyev and the chairman of MASSOLIT Michael Berlioz and their spouses move into this apartment. Soon the wives of both disappear, but this time not without a trace.
In the book, a detailed description of the above-mentioned events occupies a whole page of the 7th chapter, and in the TV series of Vladimir Bortko, a drunken Likhodeev personally tells this story to a woman at a dinner in Griboyedov House .
With the appearance of Woland in Moscow, Berlioz dies under the wheels of a tram, Likhodeev “throws evil forces” into Yalta , and Satan's retinue settles in the Bad Apartment, and because of this, the apartment finally has a bad reputation.
In the 27th chapter, the cat Begemot arranges a fire in the Bad apartment, because of which the whole house is burned. At this story, "Bad apartment" ends.
The house was built in the years 1902-1903 in the modern style . Architects - E. S. Yuditsky and A. A. Milkov . The landlord - patron of art , the owner of the tobacco factory " Ducat " Ilya Davydovich Pigit . Rooms surrendered MVZHK , as well as doctors, artists. The house was equipped with an art workshop.
An alternate version of the “bad apartment” prototype
According to the art historian and cultural expert Marina Kolotilo, there is a second possible prototype of the “bad apartment.” In the Tolstovsky House in St. Petersburg there is also a legend about the “bad apartment.” 
Author of the book “ Tolstoy House. People and Fate. ”M. N. Kolotilo in one of his articles writes:
The bad Bulgakov apartment had number 50, seven rooms and was located on the fifth floor of a five-story building. Ironically, evil spirits bad "Tolstoy" apartment has a number 60, eight rooms and is located on the sixth floor of a six-story house.- Marina Kolotilo 
In the legend of the bad "Tolstoy" apartment, recorded by the author of the book M. N. Kolotilo from the words of several elderly residents of the Tolstoy House, there are some real people and events.
For example, the book states:
In the harsh years of the Great Terror on October 1, 1937, a resident disappeared from the apartment - a consultant to the Leningrad Museum and a freelance consultant to the headquarters of the Red Army on Far Eastern issues. He never returned. As it became known much later - he was shot a month after disappearing from a bad apartment.- Marina Kolotilo 
The same book  tells about the real inhabitant of this apartment - the famous orientalist D. M. Pozdneev  , who was arrested on October 1 and shot on October 30, 1937   . The sister of D. M. Pozdneev and A. M. Pozdneev - Sofya Matveevna Pozdneeva  was married to the uncle of M. A. Bulgakov - Archpriest Peter Bulgakov (Peter Bulgakov)  . During a visit to Leningrad, M. A. Bulgakov always stayed with relatives in a bad “Tolstoy” apartment, the real number of which is 660   (in the Tolstoy apartment house there is a three-digit numbering, where the first number indicates the floor).
However, one should not confuse the “Legend of a Bad Apartment” with the mythical inhabitant and the mythical number 60 (which is a literary fiction) and the real apartment 660. Directly it is impossible to correlate and equate literary heroes and real people.
In addition, M. N. Kolotilo in the book “Tolstoy House. The constellation of names ”  showed that D. M. Pozdneev was one of the prototypes of Woland  for Mikhail Afanasyevich Bulgakov.
- Museum of Mikhail Bulgakov
- Н "Bad apartment" on Bolshaya Sadovaya will be given to the Bulgakov Foundation // Lenta.ru , November 4, 2004
- Kolotilo MN Tolstovsky house. People and destinies / Under scientific. ed. East n VG Smirnova-Volkhovsky. - SPb .: Art of Russia, 2010. - 296 pp., Ill. ISBN 978-5-98361-119-1. See: p. 274-276.
- M.N. Kolotilo . Legend of Tolstoy House .
- Kolotilo MN Tolstovsky house. People and destinies / Under scientific. ed. East n VG Smirnova-Volkhovsky. - SPb .: Art of Russia, 2010. - 296 pp., Ill. ISBN 978-5-98361-119-1 See: p. 275.
- Kolotilo MN Tolstovsky house. People and destinies / Under scientific. ed. East n VG Smirnova-Volkhovsky. - SPb .: Art of Russia, 2010. - 296 pp., Ill. ISBN 978-5-98361-119-1. See: p. 189-192.
- D.M. Pozdneev. Biography.
- Victims of political terror in the USSR. Pozdneev Dmitry Matveyevich
- Returned names. Leningrad martyrology. Pozdneev Dmitry Matveyevich (inaccessible link)
- Bulgakova Sofya Matveevna (nee Pozdneeva) (1866—1943)
- Archpriest Peter Bulgakov (Peter Bulgakov) (1861—1937)
- On the “cultural life” of Tolstovsky’s house a second book will be published // BaltInfo.ru. - November 15, 2011
- Kolotilo MN Tolstovsky house. Constellation of names / Sub scientific. ed. East n VG Smirnova-Volkhovsky. - SPb .: Art of Russia, 2011. - 392 pp.: Ill. - ISBN 978-5-98361-155-9 See p. 36-37.
- Molotov N. N. Tolstovsky house. People and destinies / Under scientific. ed. East n VG Smirnova-Volkhovsky. - SPb. : Art of Russia, 2010. - 296 p. - ISBN 978-5-98361-119-1 .