smartdraw.com - A cool website I found!
I wanted to do a blueprint of a scene and searched for a free online tool. This website has more than just house plans and mind maps, and I think it could really come in handy if you want to make some settings more approachable.
You can choose to start from scratch or use one of the many templates. The latter is probably easier in the beginning, to try out the different ways to arrange and color the objects. After getting used to the interface (it is similar to PowerPoint) you can use the result as a way to plan your scenes or give your readers a visual aid to follow the plot.
The symbols (or rather objects) for the floor plans, timelines, family trees, crime scenes etc. are sorted in many subcategories, e.g. Floor Plans -> Furniture -> Kitchen. No matter which type of diagram you pick, you can also use the objects from the others, so if you want an endoplasmic reticulum in your bathroom blueprint, go for it.
I think that for whump purposes you should especially check out the Crime Scene category for blood, drugs, weapons and so on.
I do have to say that I experienced some bugs and long loading time, but that could just be my ancient computer going wild. Also, the graphics are certainly not the prettiest. As someone who would have had to draw everything themself instead, it's still a great option.
TLDR: It's like Picrew but for locations.

















