I've always been charmed by houses, and descriptions of them are prominent in my novels. So prominent, in fact, that my editor once pointed out to me that all of my early novels had houses on the covers.
I write about the period 1933-42, and I read books written during those years: books by foreign correspondents of the time, histories of the time written contemporaneously or just afterwards, autobiographies and biographies of people who were there, present-day histories of the period, and novels written during those times.