Then I realised I could make relatively simple maps using nothing more complex than the drawing tools in Microsoft PowerPoint. Its surprising what you can achieve using just the basic shapes available. It may take a little experimentation and fiddling with the formatting of items etc but the results can be quite impressive. The main advantage of using such a simple system is it is quick and easy to learn and all that is needed is a little bit of creativity and patience. The other advantage is that once you have created one standard 'house' for instance you can copy and repeat it very easily.
Here are some examples of the sort of results I have achieved using PowerPoint. This was my map of the Bronze Citadel, a city of Hell for my last campaign. I didn't need individual houses just an overview of the regions of the city and the location of specific buildings and streets.