One of the things many people love about Windows 10 is the option for voice-guided offline navigation around the world. Microsoft has licensed HERE maps as part of the deal with Nokia and has been using them on its devices ever since. The Maps app on Windows offers you offline mode, and you can download country maps for free and use them abroad free of roaming data. Microsoft seeds occasional updates for the offline maps. Such update is available now, and the Windows 10 users can find it Settings>System>Offline Maps. If you want to use the latest maps with the most recent updates, you should go and update yours. The update can be found on Windows 10 and Windows 10 Mobile. We can't confirm it on Windows Phone 8 and Windows 8 though. Feel free to share your experience in our comments...
Source: http://www.gsmarena.com/a_new_update_for_the_offline_map_data_on_windows_10_available_now-news-16403.php