I agree they don't have to be, but a sense of authenticity of location can really add to the atmosphere of a novel. For example, in "Mrs Dalloway", you can literally retrace the steps of Mrs Dalloway through St James' park and St James' and on to Bloomsbury. The descriptions are incredibly precise and totally accurate. Likewise people walk through Dublin visiting the exact scenes depicted in "Ulysses".
Another example (slightly obscure) from London is "The Book of Dave" by Will Self, which is partly set in a post-apocalyptic future. The geography is very thoughtfully handled, but in this future the Thames has flooded and lots of London is underwater. Part of the fun is figuring out which bits of present London they are referring to when they talk about landmarks etc which survive[1].
Now it's fair to say all those examples are shooting a lot higher-brow than Dan Brown, but another example more similar in genre aesthetic to Dan Brown would be John LeCarre's "Smiley" novels (eg "The spy who came in from the cold" etc). To the extent I know the locations in the ones I have read, they seem to me very authentically described, which greatly enhances my sense of immersion in the atmosphere.
[1] eg "centrul stack" I'm pretty sure is the wreck of the Centerpoint Building, now an empty shell filled with seabirds.
Another example (slightly obscure) from London is "The Book of Dave" by Will Self, which is partly set in a post-apocalyptic future. The geography is very thoughtfully handled, but in this future the Thames has flooded and lots of London is underwater. Part of the fun is figuring out which bits of present London they are referring to when they talk about landmarks etc which survive[1].
Now it's fair to say all those examples are shooting a lot higher-brow than Dan Brown, but another example more similar in genre aesthetic to Dan Brown would be John LeCarre's "Smiley" novels (eg "The spy who came in from the cold" etc). To the extent I know the locations in the ones I have read, they seem to me very authentically described, which greatly enhances my sense of immersion in the atmosphere.
[1] eg "centrul stack" I'm pretty sure is the wreck of the Centerpoint Building, now an empty shell filled with seabirds.