Being books 3 and 4 in the Rivers of London/Peter Grant series by Ben Aaronovitch.
I really love the world that Ben Aaronovitch has created, and the way it is totally grounded in police procedure - and the way he can get round any tiresome police procedure by having the Folly as a semi-independent body which can make up the rules here and there. After all, it's a police department consisting of two and a half members at the moment, Lesley being officially still on sick leave after the events of Rivers of London (plus spooky servant and dog, of course). My Young Man is a PCSO, and I spent four years working for the Met as a Clerical Officer (as it was then, in the mists of time before computers), and all the police stuff really rings true.
So Whispers Underground takes us to the Underground system and the sewers, via the murder of an American student - which also brings in the FBI, as said student is the son of a senator. There's a lot of history about the building of the tunnels, and Ben Aaronovitch also takes a look at the world of modern art on the way, as well as continuing the plot lines concerning the Faceless Man (who almost killed Peter in Moon over Soho) and the river spirits of the city.
In Broken Homes, we go up into the high-rise flats of Skygarden, one of the post-war rebuilding projects that didn't quite create the brave new world the architects were aiming for.
I grew up not far from some much smaller scale high rise flats, at Kersal in Salford, which were early enough to still have coal fires, and badly designed enough that the only way to get the coal to the flats was in the passenger lift. They were mostly blown up in the 1980s - one block, now privately owned, still survives - and there is a website somewhere that has collected the memories of people who lived there, who were mostly really, really pleased to get out of the Victorian terraces of Salford to somewhere they could see rabbits from their balconies at the beginning.
In Ben Aaronovitch's version of reality, of course the Skygarden estate was built with magical principles in mind, and some of what he describes turns out to be real architectural ideas.
Along with the exciting action and interesting characters, he packs a lot of information into the books about London history and all sorts of other things, like the architecture here. Peter Grant has quite a few things to say about the design deficiencies of the flats, and one of the other characters shows him what the original vision for the building had been - literally a garden in the sky.
Along the way, they also encounter magical markets and demon traps, and start to discover more about the international magical scene.
I'm really looking forward to the next book coming out - and not just because Broken Homes ended on such a cliff hanger!