I was wondering if anyone knows of a downloadable list of all cities and towns in the world.
Can someone suggest a resource that has a comprehensive list city and town names?
You can try the Geonames database.
The GeoNames geographical database covers all countries and contains over eleven million placenames that are available for download free of charge.
You may have to subselect it as it contains many geographic names that are not cities or towns. With advanced search, you can select the feature city, village, … that may contain what you need, although I don't think it has the size so it may contain a large number of localities too small to be usually considered city or town.