Fun fact: Hilbert was born in Königsberg, a port city on the Baltic with a famous set of 7 bridges, and as part of the WWII peace settlement between the allies, Russia got it. But not without some interest stipulations.
Königsberg is now Kaliningrad, in the Kaliningrad Oblast, a geographically separated province of Russia. In order for Russia to regain direct access to the Kalingrad port (Königsberg), Russia would have to invade either Lithuania or Poland. And if you look at the borders, it's pretty clear they were designed as a lock: a straight shot from the nearest point in Russia would go through Lithuania, then Poland, and Lithuania again.
https://www.amazon.com/Hilbert-Constance-Reid/dp/0387946748/
It is excellent both for understanding his life, and slips in the subtle philosophical points that he introduced to mathematics. (Like what mathematical existence should mean in his view.) And yet manages to be appropriate for a general audience with no knowledge of math. I know of no better explanation for a lay audience of where Formalism, the philosophy of math that most mathematicians officially subscribe to, actually came from.