I made (the beginnings of) a map of the London-area locations mentioned throughout the first section of Thomas Pynchon's Gravity's Rainbow. By themselves, they aren't really that interesting (it's just a map of various locales of the West End and East End). However, when they are cross-referenced with the historical context within which Pynchon is writing, one finds that these locales map perfectly onto some of the most bombed sites of both the 1940-1941 London Blitz, as well as the V-weapons offensive of 1944-1945 (the University of Portsmouth and the JISC's Bomb Sight project gives you a great interactive mapping of the British Bomb Census to reference against Pynchon's fictional mapping of London).

If this were the only interesting thing about Pynchon's mapping of London, then I could just use the Bomb Sight map. Here's the other side of it, which can't really be mapped in any intuitive way (that I can think of): The first section of Gravity's Rainbow is very concerned with Poisson Distributions and what they allow someone to learn about seemingly random and unrelated events. Throughout this section of the novel, one character calculates a Poisson Distribution that allows him to predict where the rockets will hit (calculating where bombs will hit during the London Blitz and cross-referencing the results with the Bomb Census information is actually one a common method of teaching/learning Poisson Distributions) and attempts to match it with the actions of an American soldier whose erections in certain London areas are followed 2-10 days afterward by a V-2 rocket strike. Thus, mapping Pynchon's London takes on a metareferential quality: you end up mapping something that is meant to show how information is gleaned from (and even constructed by) the linkages of seemingly unrelated pieces of information. In other words, you're mapping the process of a mapping.

(This doesn't even get into the issue of vaguely mappable or differentially mapped entities in the novel, such as the SOE and "The White Visitation." It's an important concern I couldn't touch on here.)

Map here: https://uploads.knightlab.com/storymapjs/11e0920873f6e8fc833186b1dd010fbe/gravitys-rainbow-east-end-map/index.html