Did you know…
…that there were no castles in medieval Russia? All right, so I have to qualify that: there were military border outposts with villages around them, with fortifications and miscellaneous buildings. They were built mostly on rivers, that is on trade routes, and at strategic points against attacks by steppes nomads. So one could say that there were castles in medieval Russia, although I would prefer to call them fortresses.
But there were no castles as centers of a fief, no castles as residences of the lord of the land. No lord of the manor, no baron entrenched in his barony (or count in his county, or duke in his duchy, or…oh, enough).
What could be called the Russian nobility, in the middle ages, consisted of princes and boyars. Princes were rulers of principalities, while boyars were essentially wealthy landowners (that is, they owned land personally rather than held it in fief for their liege). Both boyars and princes lived mostly in cities and conducted their business from there.
Country estates were run by stewards. Princes, who derived their income from taxes, did a yearly round of the lands they ruled (but did not necessarily own). Landowners received income from their lands, on which free and unfree men worked. What they expected to receive was established beforehand, something like a rent, rather than an arbitrary collection of goods.
But the boyars themselves remained in the cities, the political and economic centers of the land where their properties were located. The large urban estates where they lived, as they did in Novgorod, would more readily qualify as castles than anything else. These estates were enclosed in wooden palisades and comprised many buildings, besides the boyar’s residence: houses and workshops for the craftsmen, lodging for the servants, storage buildings, barns and stables, etc. This arrangement put the boyars right where all the important decisions were made: the cities themselves.