The aim of this chapter is to analyse and compare the world-building styles of two contemporary British urban fantasy novels—Neverwhere by Neil Gaiman and the first volume of the Rivers of London series by Ben Aaronovitch. The chapter focuses on the role of the setting by mapping specific locations and analysing the urban spaces depicted in these works. The central theme of this chapter is the city of London and its influence on literary works. The two novels in question combine elements of the real urban environment of London with a fantastical setting. The theoretical section of this paper situates these works within the genre of urban fantasy and discusses the concepts of literary geography and cartography as theories of literary mapping. Additionally, the chapter focuses on specific London locations featured in both novels, investigating the role of settings, the function of these places within the narratives, and the boundary between reality and fantasy. By mapping real places and their fantastical representations, this study aims to demonstrate how urban spaces are reshaped and perceived in literature.