While few readers of historical fiction want pages of tedious and meticulous description, the setting of a novel is nevertheless critical to its ability to evoke an age and essential to its authenticity. Like anachronistic costumes or inappropriate language, an unrealistic setting can kill an otherwise brilliant book.
The problem is two-fold. First, authors of historical fiction need to do comprehensive research on the architecture, furnishings and domestic art of the period of their works in order to accurately depict the domestic and public settings of the action of their novels. Second, the prejudices and misconceptions of readers about many time-period's need to be over-come and gently corrected.
Let me give you an example. A contemporary visitor described a mansion in which the windows opened on either the sea or "delicious gardens." It had walls panelled with plaques of polychrome marble. It had vaulted ceilings painted to resemble the night sky. It had a great salon with a central fountain surrounded by mosaics depicting the waves of the sea.
Where and in what century do you think this palace was built?
A) 4th Century Byzantium
B) 13th Century Jerusalem
C) 15th Century Italy
D) 17th Century Britain
The correct answer is B -- and an early 13th century at that! The description dates from 1212, and the palace itself would therefore have been built several years earlier, veritably on the start of the 13th century. The palace, incidentally, was not even a royal one, but the residence of the Lord of Beirut, John d'Ibelin.
Yet I have read many a book (not to mention seen many films) set in this time period where the lords and kings are depicted huddling around fires in dark, gloomy and smokey castles of rough-hewn stone surrounded by fowl and dogs scratching in the straw on the floor. Now some of that may be attributable to location (i.e. the more "civilized" East described above compared to the cold outer edges of Europe such as Scotland and Scandinavia), but far too many of these books portraying the nobility of the 13th century living practically in caves are set in the heart of Europe -- France, the Holy Roman Empire, Spain.
Correcting the misconceptions created by generations of earlier writers is a great challenge. As an academic, it is tempting to site sources. Or, with ebooks, its tempting to include photographs of contemporary art (to the extent these exist.) But ultimately, I think it all comes down to credibility. If an author does a good enough job of describing the world of the novel in other aspects -- dress, weapons, technology, social attitudes and customs -- the reader will, maybe reluctantly at first, begin to believe the descriptions of the setting as well. I hope....