There is no writing tool more valuable than imagination. The facility for crafting prose is a poor second, because if there is nothing in front of the inner eye, there is nothing for the prose to express.
I am sure all writers have different methods for strengthening and stimulating their imagination. I do not naturally think in visual terms, and in recent years I've found the internet very useful not only for training my visual faculty, but also for providing 'models' around which I can write. Both Dragonchaser and The Dog of the North drew both inspiration and topographical information from the wonderful antique maps of Braun and Hogenberg. The one shown below, of Loreto, has never featured in one of my stories, but I do own a 16th century original of this map.
For The Last Free City I have used maps of another mediaeval city. Because that city is relatively unchanged today, I've also harvested a collection of photographs from the web which I've put into a phyisical file. I can use this for inspiration and also for "blocking out" scenes. Here are a couple of my favourite images:
The Last Free City
The Road to Grandille
Naturally these pictures are all of a 'real' place: my customary non-existent prize for anyone who can tell me where this is.
How do you go about visualising your locations?