About The Three Golden Keys by Peter Sís: Through the images and texts, the reader follows a trail of memories of the city through each of the year's seasons, and inbetweentimes learns of some of its legends, each one a golden key for unlocking the past.
Somehow, this brief description really appealed to me, but I made a note of it and forgot it. Today I found it again, and looking further, I also found Peter Sis's website. It's beautifully designed, and has animated excerpts from each of his books. Take a look!
(After posting this, I realised where I had read about it: in the excellent Giornale Nuovo. Misteraitch's post about it includes a number of illustrations from the book.)