The context:
He had seen it lying in the window of a frowsy little junk-shop in a slummy quarter of the town (just what quarter he did not now remember) and had been stricken immediately by an overwhelming desire to possess it
Just to elaborate a little bit more on what I was confused about. The sentence seems to be a declarative sentence but somehow inverted to me and lacks something. (however, when I read it out loud, it sounds perfect to me).
My understanding/way of expressing the content would be:
He did not remember now just which quarter it was.
Could someone help me explain the grammar of this sentence please? And if possible, could you give me more similar examples please?