The Pillbox Map Layer Project (PBMLP) is a project started in the UK to map WW1 and WW2 defensive structures. The project up until now has been web based and this is an app that uses the same data source. The app is free to use and has no subscription or user restrictions. Your location information will be requested however is not required for the app to work. This will be the first release with more features coming in the future.