Love seeing my daughter (and son) play with their London in a Bag. We bought it from The Handpicked Collection last year as a Christmas gift. So sweet they actually recognise so many of these buildings (and people!).
Also can't go wrong with the city/country in a box collection from Muji. Pick from London, New York, Paris, Italy and Germany. In fact, their entire line of wooden toys is incredibly sweet.
And so is their Christmas decor (and all very inexpensive too):