With the adoption of Communism in the Soviet Union, what happened to private property and those who occupied it? Did landowners (including the oligarchy and simpler land owners) retain any rights to "their" property? Were they permitted to stay in their residencies or were they moved to communal apartments? If they were moved out, did the Soviet union destroy these private homes or house troops with in them? Did this change throughout the communist period?
Legal definition changed over time, but in practice the situation was perfectly defined by Constitution of USSR (1936), Article 6: "Land, its interior, waters, forests [...] and buildings are property of the state". (Note that USSR had not concept of real estate as a single entity - land, buildings on it and its natural resources were all separate legal entities) In fact, USSR law only had two types of property defined: socialistic (i.e state property) and cooperative (i.e. owned by a kolkhoz, for example). And since cooperative property was effectively a property of a government organization, they were in practice mostly treated as one and the same. Thus, anyone owning land and/or buildings in USSR had it confiscated - simple as that.
It didn't happen at once, though, but the main point relevant to the question was August 20, 1918, when a Decree of VTsIK (which is surprisingly hard to find in English, so here's a Russian version) stated that in the cities with population over 10000 all real estate was transferred to state and its usage was to be regulated by municipal government. For example, in Moscow if a residential building housed less than standard (~9m2 per resident) it was to be converted to communal apartment - in this case previous residents still lived there, but had less living space.
This gradual removal of personal property continued for quite a long time, and was only set in stone in 1936 Constitution of USSR, and after that any and all land and buildings were owned only by the state until 1988, when it was allowed to sell apartments and houses to citizens, although only one real estate item could be sold to a family, and it had to be either the one they are currently residing in, or a newly-built apartment or house. This situation remained until dissolution of USSR, and by then only 0.09% of residences in USSR were privately-owned.